Electron configuration

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Electron atomic and molecular orbitals

A Bohr diagram of lithium

In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals.^[1] For example, the electron configuration of the neon atom is 1s² 2s² 2p⁶.

Electronic configurations describe each electron as moving independently in an orbital, in an average field created by all other orbitals. Mathematically, configurations are described by Slater determinants or configuration state functions.

According to the laws of quantum mechanics, for systems with only one electron, an energy is associated with each electron configuration and, upon certain conditions, electrons are able to move from one configuration to another by the emission or absorption of a quantum of energy, in the form of a photon.

Knowledge of the electron configuration of different atoms is useful in understanding the structure of the periodic table of elements. This is also useful for describing the chemical bonds that hold atoms together. In bulk materials, this same idea helps explain the peculiar properties of lasers and semiconductors.

Shells and subshells

	s (ℓ=0)	p (ℓ=1)
	m=0	m=0	m=±1
	s	pz	px	py
n=1
n=2

Electron configuration was first conceived of under the Bohr model of the atom, and it is still common to speak of shells and subshells despite the advances in understanding of the quantum-mechanical nature of electrons.

An electron shell is the set of allowed states that share the same principal quantum number, n (the number before the letter in the orbital label), that electrons may occupy. An atom's nth electron shell can accommodate 2n² electrons, e.g. the first shell can accommodate 2 electrons, the second shell 8 electrons, and the third shell 18 electrons. The factor of two arises because the allowed states are doubled due to electron spin—each atomic orbital admits up to two otherwise identical electrons with opposite spin, one with a spin +1/2 (usually denoted by an up-arrow) and one with a spin −1/2 (with a down-arrow).

A subshell is the set of states defined by a common azimuthal quantum number, ℓ, within a shell. The values ℓ = 0, 1, 2, 3 correspond to the s, p, d, and f labels, respectively. For example, the 3d subshell has n = 3 and ℓ = 2. The maximum number of electrons that can be placed in a subshell is given by 2(2ℓ+1). This gives two electrons in an s subshell, six electrons in a p subshell, ten electrons in a d subshell and fourteen electrons in an f subshell.

The numbers of electrons that can occupy each shell and each subshell arise from the equations of quantum mechanics,^[2] in particular the Pauli exclusion principle, which states that no two electrons in the same atom can have the same values of the four quantum numbers.^[3]

Notation

Physicists and chemists use a standard notation to indicate the electron configurations of atoms and molecules. For atoms, the notation consists of a sequence of atomic subshell labels (e.g. for phosphorus the sequence 1s, 2s, 2p, 3s, 3p) with the number of electrons assigned to each subshell placed as a superscript. For example, hydrogen has one electron in the s-orbital of the first shell, so its configuration is written 1s¹. Lithium has two electrons in the 1s-subshell and one in the (higher-energy) 2s-subshell, so its configuration is written 1s² 2s¹ (pronounced "one-s-two, two-s-one"). Phosphorus (atomic number 15) is as follows: 1s² 2s² 2p⁶ 3s² 3p³.
For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. The electron configuration can be visualized as the core electrons, equivalent to the noble gas of the preceding period, and the valence electrons: each element in a period differs only by the last few subshells. Phosphorus, for instance, is in the third period. It differs from the second-period neon, whose configuration is 1s² 2s² 2p⁶, only by the presence of a third shell. The portion of its configuration that is equivalent to neon is abbreviated as [Ne], allowing the configuration of phosphorus to be written as [Ne] 3s² 3p³ rather than writing out the details of the configuration of neon explicitly. This convention is useful as it is the electrons in the outermost shell that most determine the chemistry of the element.

For a given configuration, the order of writing the orbitals is not completely fixed since only the orbital occupancies have physical significance. For example, the electron configuration of the titanium ground state can be written as either [Ar] 4s² 3d² or [Ar] 3d² 4s². The first notation follows the order based on the Madelung rule for the configurations of neutral atoms; 4s is filled before 3d in the sequence Ar, K, Ca, Sc, Ti. The second notation groups all orbitals with the same value of n together, corresponding to the "spectroscopic" order of orbital energies that is the reverse of the order in which electrons are removed from a given atom to form positive ions; 3d is filled before 4s in the sequence Ti⁴⁺, Ti³⁺, Ti²⁺, Ti⁺, Ti.

The superscript 1 for a singly occupied subshell is not compulsory; for example aluminium may be written as either [Ne] 3s² 3p¹ or [Ne] 3s² 3p. It is quite common to see the letters of the orbital labels (s, p, d, f) written in an italic or slanting typeface, although the International Union of Pure and Applied Chemistry (IUPAC) recommends a normal typeface (as used here). The choice of letters originates from a now-obsolete system of categorizing spectral lines as "sharp", "principal", "diffuse" and "fundamental" (or "fine"), based on their observed fine structure: their modern usage indicates orbitals with an azimuthal quantum number, l, of 0, 1, 2 or 3 respectively. After "f", the sequence continues alphabetically "g", "h", "i"... (l = 4, 5, 6...), skipping "j", although orbitals of these types are rarely required.^[4][5]

The electron configurations of molecules are written in a similar way, except that molecular orbital labels are used instead of atomic orbital labels (see below).

Energy — ground state and excited states

The energy associated to an electron is that of its orbital. The energy of a configuration is often approximated as the sum of the energy of each electron, neglecting the electron-electron interactions. The configuration that corresponds to the lowest electronic energy is called the ground state. Any other configuration is an excited state.

As an example, the ground state configuration of the sodium atom is 1s²2s²2p⁶3s¹, as deduced from the Aufbau principle (see below). The first excited state is obtained by promoting a 3s electron to the 3p orbital, to obtain the 1s²2s²2p⁶3p configuration, abbreviated as the 3p level. Atoms can move from one configuration to another by absorbing or emitting energy. In a sodium-vapor lamp for example, sodium atoms are excited to the 3p level by an electrical discharge, and return to the ground state by emitting yellow light of wavelength 589 nm.

Usually, the excitation of valence electrons (such as 3s for sodium) involves energies corresponding to photons of visible or ultraviolet light. The excitation of core electrons is possible, but requires much higher energies, generally corresponding to x-ray photons. This would be the case for example to excite a 2p electron to the 3s level and form the excited 1s²2s²2p⁵3s² configuration.

The remainder of this article deals only with the ground-state configuration, often referred to as "the" configuration of an atom or molecule.

History

Niels Bohr (1923) was the first to propose that the periodicity in the properties of the elements might be explained by the electronic structure of the atom.^[6] His proposals were based on the then current Bohr model of the atom, in which the electron shells were orbits at a fixed distance from the nucleus. Bohr's original configurations would seem strange to a present-day chemist: sulfur was given as 2.4.4.6 instead of 1s² 2s² 2p⁶ 3s² 3p⁴ (2.8.6).

The following year, E. C. Stoner incorporated Sommerfeld's third quantum number into the description of electron shells, and correctly predicted the shell structure of sulfur to be 2.8.6.^[7] However neither Bohr's system nor Stoner's could correctly describe the changes in atomic spectra in a magnetic field (the Zeeman effect).

Bohr was well aware of this shortcoming (and others), and had written to his friend Wolfgang Pauli to ask for his help in saving quantum theory (the system now known as "old quantum theory"). Pauli realized that the Zeeman effect must be due only to the outermost electrons of the atom, and was able to reproduce Stoner's shell structure, but with the correct structure of subshells, by his inclusion of a fourth quantum number and his exclusion principle (1925):^[8]

It should be forbidden for more than one electron with the same value of the main quantum number n to have the same value for the other three quantum numbers k [l], j [m_l] and m [m_s].

The Schrödinger equation, published in 1926, gave three of the four quantum numbers as a direct consequence of its solution for the hydrogen atom:^[2] this solution yields the atomic orbitals that are shown today in textbooks of chemistry (and above). The examination of atomic spectra allowed the electron configurations of atoms to be determined experimentally, and led to an empirical rule (known as Madelung's rule (1936),^[9] see below) for the order in which atomic orbitals are filled with electrons.

Atoms: Aufbau principle and Madelung rule

The Aufbau principle (from the German Aufbau, "building up, construction") was an important part of Bohr's original concept of electron configuration. It may be stated as:^[10]

a maximum of two electrons are put into orbitals in the order of increasing orbital energy: the lowest-energy orbitals are filled before electrons are placed in higher-energy orbitals.

The approximate order of filling of atomic orbitals, following the arrows from 1s to 7p. (After 7p the order includes orbitals outside the range of the diagram, starting with 8s.)

The principle works very well (for the ground states of the atoms) for the first 18 elements, then decreasingly well for the following 100 elements. The modern form of the Aufbau principle describes an order of orbital energies given by Madelung's rule (or Klechkowski's rule). This rule was first stated by Charles Janet in 1929, rediscovered by Erwin Madelung in 1936,^[9] and later given a theoretical justification by V.M. Klechkowski^[11]

1. Orbitals are filled in the order of increasing n+l;
2. Where two orbitals have the same value of n+l, they are filled in order of increasing n.

This gives the following order for filling the orbitals:

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, (8s, 5g, 6f, 7d, 8p, and 9s)

In this list the orbitals in parentheses are not occupied in the ground state of the heaviest atom now known (Og, Z = 118).

The Aufbau principle can be applied, in a modified form, to the protons and neutrons in the atomic nucleus, as in the shell model of nuclear physics and nuclear chemistry.

Periodic table

Electron configuration table

The form of the periodic table is closely related to the electron configuration of the atoms of the elements. For example, all the elements of group 2 have an electron configuration of [E] ns² (where [E] is an inert gas configuration), and have notable similarities in their chemical properties. In general, the periodicity of the periodic table in terms of periodic table blocks is clearly due to the number of electrons (2, 6, 10, 14...) needed to fill s, p, d, and f subshells.

The outermost electron shell is often referred to as the "valence shell" and (to a first approximation) determines the chemical properties. It should be remembered that the similarities in the chemical properties were remarked on more than a century before the idea of electron configuration.^[12] It is not clear how far Madelung's rule explains (rather than simply describes) the periodic table,^[13] although some properties (such as the common +2 oxidation state in the first row of the transition metals) would obviously be different with a different order of orbital filling.

Shortcomings of the Aufbau principle

The Aufbau principle rests on a fundamental postulate that the order of orbital energies is fixed, both for a given element and between different elements; in both cases this is only approximately true. It considers atomic orbitals as "boxes" of fixed energy into which can be placed two electrons and no more. However, the energy of an electron "in" an atomic orbital depends on the energies of all the other electrons of the atom (or ion, or molecule, etc.). There are no "one-electron solutions" for systems of more than one electron, only a set of many-electron solutions that cannot be calculated exactly^[14] (although there are mathematical approximations available, such as the Hartree–Fock method).

The fact that the Aufbau principle is based on an approximation can be seen from the fact that there is an almost-fixed filling order at all, that, within a given shell, the s-orbital is always filled before the p-orbitals. In a hydrogen-like atom, which only has one electron, the s-orbital and the p-orbitals of the same shell have exactly the same energy, to a very good approximation in the absence of external electromagnetic fields. (However, in a real hydrogen atom, the energy levels are slightly split by the magnetic field of the nucleus, and by the quantum electrodynamic effects of the Lamb shift.)

Ionization of the transition metals

The naïve application of the Aufbau principle leads to a well-known paradox (or apparent paradox) in the basic chemistry of the transition metals. Potassium and calcium appear in the periodic table before the transition metals, and have electron configurations [Ar] 4s¹ and [Ar] 4s² respectively, i.e. the 4s-orbital is filled before the 3d-orbital. This is in line with Madelung's rule, as the 4s-orbital has n+l  = 4 (n = 4, l = 0) while the 3d-orbital has n+l  = 5 (n = 3, l = 2). After calcium, most neutral atoms in the first series of transition metals (Sc-Zn) have configurations with two 4s electrons, but there are two exceptions. Chromium and copper have electron configurations [Ar] 3d⁵ 4s¹ and [Ar] 3d¹⁰ 4s¹ respectively, i.e. one electron has passed from the 4s-orbital to a 3d-orbital to generate a half-filled or filled subshell. In this case, the usual explanation is that "half-filled or completely filled subshells are particularly stable arrangements of electrons".

The apparent paradox arises when electrons are removed from the transition metal atoms to form ions. The first electrons to be ionized come not from the 3d-orbital, as one would expect if it were "higher in energy", but from the 4s-orbital. This interchange of electrons between 4s and 3d is found for all atoms of the first series of transition metals.^[15] The configurations of the neutral atoms (K, Ca, Sc, Ti, V, Cr, ...) usually follow the order 1s, 2s, 2p, 3s, 3p, 4s, 3d, ...; however the successive stages of ionization of a given atom (such as Fe⁴⁺, Fe³⁺, Fe²⁺, Fe⁺, Fe) usually follow the order 1s, 2s, 2p, 3s, 3p, 3d, 4s, ...

This phenomenon is only paradoxical if it is assumed that the energy order of atomic orbitals is fixed and unaffected by the nuclear charge or by the presence of electrons in other orbitals. If that were the case, the 3d-orbital would have the same energy as the 3p-orbital, as it does in hydrogen, yet it clearly doesn't. There is no special reason why the Fe²⁺ ion should have the same electron configuration as the chromium atom, given that iron has two more protons in its nucleus than chromium, and that the chemistry of the two species is very different. Melrose and Eric Scerri have analyzed the changes of orbital energy with orbital occupations in terms of the two-electron repulsion integrals of the Hartree-Fock method of atomic structure calculation.^[16] More recently Scerri has argued that contrary to what is stated in the vast majority of sources including the title of his previous article on the subject, 3d orbitals rather than 4s are in fact preferentially occupied.^[17]

Similar ion-like 3d^x4s⁰ configurations occur in transition metal complexes as described by the simple crystal field theory, even if the metal has oxidation state 0. For example, chromium hexacarbonyl can be described as a chromium atom (not ion) surrounded by six carbon monoxide ligands. The electron configuration of the central chromium atom is described as 3d⁶ with the six electrons filling the three lower-energy d orbitals between the ligands. The other two d orbitals are at higher energy due to the crystal field of the ligands. This picture is consistent with the experimental fact that the complex is diamagnetic, meaning that it has no unpaired electrons. However, in a more accurate description using molecular orbital theory, the d-like orbitals occupied by the six electrons are no longer identical with the d orbitals of the free atom.

Other exceptions to Madelung's rule

There are several more exceptions to Madelung's rule among the heavier elements, and as atomic number increases it becomes more and more difficult to find simple explanations such as the stability of half-filled subshells. It is possible to predict most of the exceptions by Hartree–Fock calculations,^[18] which are an approximate method for taking account of the effect of the other electrons on orbital energies. For the heavier elements, it is also necessary to take account of the effects of Special Relativity on the energies of the atomic orbitals, as the inner-shell electrons are moving at speeds approaching the speed of light. In general, these relativistic effects^[19] tend to decrease the energy of the s-orbitals in relation to the other atomic orbitals.^[20] The table below shows the ground state configuration in terms of orbital occupancy, but it does not show the ground state in terms of the sequence of orbital energies as determined spectroscopically. For example, in the transition metals, the 4s orbital is of a higher energy than the 3d orbitals; and in the lanthanides, the 6s is higher than the 4f and 5d. The ground states can be seen in the Electron configurations of the elements (data page).

Electron shells filled in violation of Madelung's rule^[21] (red)

Period 4				Period 5				Period 6				Period 7
Element	Z	Electron Configuration		Element	Z	Electron Configuration		Element	Z	Electron Configuration		Element	Z	Electron Configuration
								Lanthanum	57	[Xe] 6s2 5d1		Actinium	89	[Rn] 7s2 6d1
								Cerium	58	[Xe] 6s2 4f1 5d1		Thorium	90	[Rn] 7s2 6d2
								Praseodymium	59	[Xe] 6s2 4f3		Protactinium	91	[Rn] 7s2 5f2 6d1
								Neodymium	60	[Xe] 6s2 4f4		Uranium	92	[Rn] 7s2 5f3 6d1
								Promethium	61	[Xe] 6s2 4f5		Neptunium	93	[Rn] 7s2 5f4 6d1
								Samarium	62	[Xe] 6s2 4f6		Plutonium	94	[Rn] 7s2 5f6
								Europium	63	[Xe] 6s2 4f7		Americium	95	[Rn] 7s2 5f7
								Gadolinium	64	[Xe] 6s2 4f7 5d1		Curium	96	[Rn] 7s2 5f7 6d1
								Terbium	65	[Xe] 6s2 4f9		Berkelium	97	[Rn] 7s2 5f9
Scandium	21	[Ar] 4s2 3d1		Yttrium	39	[Kr] 5s2 4d1		Lutetium	71	[Xe] 6s2 4f14 5d1		Lawrencium	103	[Rn] 7s2 5f14 7p1
Titanium	22	[Ar] 4s2 3d2		Zirconium	40	[Kr] 5s2 4d2		Hafnium	72	[Xe] 6s2 4f14 5d2		Rutherfordium	104	[Rn] 7s2 5f14 6d2
Vanadium	23	[Ar] 4s2 3d3		Niobium	41	[Kr] 5s1 4d4		Tantalum	73	[Xe] 6s2 4f14 5d3		Dubnium	105	[Rn] 7s2 5f14 6d3
Chromium	24	[Ar] 4s1 3d5		Molybdenum	42	[Kr] 5s1 4d5		Tungsten	74	[Xe] 6s2 4f14 5d4		Seaborgium	106	[Rn] 7s2 5f14 6d4
Manganese	25	[Ar] 4s2 3d5		Technetium	43	[Kr] 5s2 4d5		Rhenium	75	[Xe] 6s2 4f14 5d5		Bohrium	107	[Rn] 7s2 5f14 6d5
Iron	26	[Ar] 4s2 3d6		Ruthenium	44	[Kr] 5s1 4d7		Osmium	76	[Xe] 6s2 4f14 5d6		Hassium	108	[Rn] 7s2 5f14 6d6
Cobalt	27	[Ar] 4s2 3d7		Rhodium	45	[Kr] 5s1 4d8		Iridium	77	[Xe] 6s2 4f14 5d7
Nickel	28	[Ar] 4s2 3d8 or [Ar] 4s1 3d9 (disputed)[22]		Palladium	46	[Kr] 4d10		Platinum	78	[Xe] 6s1 4f14 5d9
Copper	29	[Ar] 4s1 3d10		Silver	47	[Kr] 5s1 4d10		Gold	79	[Xe] 6s1 4f14 5d10
Zinc	30	[Ar] 4s2 3d10		Cadmium	48	[Kr] 5s2 4d10		Mercury	80	[Xe] 6s2 4f14 5d10

The electron-shell configuration of elements beyond hassium has not yet been empirically verified, but they are expected to follow Madelung's rule without exceptions until element 120.^[23]

Electron configuration in molecules

In molecules, the situation becomes more complex, as each molecule has a different orbital structure. The molecular orbitals are labelled according to their symmetry,^[24] rather than the atomic orbital labels used for atoms and monatomic ions: hence, the electron configuration of the dioxygen molecule, O₂, is written 1σ_g² 1σ_u² 2σ_g² 2σ_u² 3σ_g² 1π_u⁴ 1π_g²,^[25][26] or equivalently 1σ_g² 1σ_u² 2σ_g² 2σ_u² 1π_u⁴ 3σ_g² 1π_g².^[1] The term 1π_g² represents the two electrons in the two degenerate π*-orbitals (antibonding). From Hund's rules, these electrons have parallel spins in the ground state, and so dioxygen has a net magnetic moment (it is paramagnetic). The explanation of the paramagnetism of dioxygen was a major success for molecular orbital theory.

The electronic configuration of polyatomic molecules can change without absorption or emission of a photon through vibronic couplings.

Electron configuration in solids

In a solid, the electron states become very numerous. They cease to be discrete, and effectively blend into continuous ranges of possible states (an electron band). The notion of electron configuration ceases to be relevant, and yields to band theory.

Applications

The most widespread application of electron configurations is in the rationalization of chemical properties, in both inorganic and organic chemistry. In effect, electron configurations, along with some simplified form of molecular orbital theory, have become the modern equivalent of the valence concept, describing the number and type of chemical bonds that an atom can be expected to form.

This approach is taken further in computational chemistry, which typically attempts to make quantitative estimates of chemical properties. For many years, most such calculations relied upon the "linear combination of atomic orbitals" (LCAO) approximation, using an ever-larger and more complex basis set of atomic orbitals as the starting point. The last step in such a calculation is the assignment of electrons among the molecular orbitals according to the Aufbau principle. Not all methods in calculational chemistry rely on electron configuration: density functional theory (DFT) is an important example of a method that discards the model.

For atoms or molecules with more than one electron, the motion of electrons are correlated and such a picture is no longer exact. A very large number of electronic configurations are needed to exactly describe any multi-electron system, and no energy can be associated with one single configuration. However, the electronic wave function is usually dominated by a very small number of configurations and therefore the notion of electronic configuration remains essential for multi-electron systems.

A fundamental application of electron configurations is in the interpretation of atomic spectra. In this case, it is necessary to supplement the electron configuration with one or more term symbols, which describe the different energy levels available to an atom. Term symbols can be calculated for any electron configuration, not just the ground-state configuration listed in tables, although not all the energy levels are observed in practice. It is through the analysis of atomic spectra that the ground-state electron configurations of the elements were experimentally determined

Brønsted–Lowry acid–base theory

The Brønsted–Lowry theory is an acid–base reaction theory which was proposed independently by Johannes Nicolaus Brønsted and Thomas Martin Lowry in 1923.^[1][2] The fundamental concept of this theory is that when an acid and a base react with each other, the acid forms its conjugate base, and the base forms its conjugate acid by exchange of a proton (the hydrogen cation, or H⁺). This theory is a generalization of the Arrhenius theory.

Definitions of acids and bases



Johannes Nicolaus Brønsted and Thomas Martin Lowry, independently, formulated the idea that acids are proton (H⁺) donors while bases are proton acceptors.

In the Arrhenius theory acids are defined as substances which dissociate in aqueous solution to give H⁺ (hydrogen ions). Bases are defined as substances which dissociate in aqueous solution to give OH⁻ (hydroxide ions).^[3]

In 1923 physical chemists Johannes Nicolaus Brønsted in Denmark and Thomas Martin Lowry in England independently proposed the theory that carries their names.^[4][5][6] In the Brønsted–Lowry theory acids and bases are defined by the way they react with each other, which allows for greater generality. The definition is expressed in terms of an equilibrium expression



acid + base ⇌ conjugate base + conjugate acid.


With an acid, HA, the equation can be written symbolically as:


 

HA + B ⇌ A⁻ + HB⁺


The equilibrium sign, ⇌, is used because the reaction can occur in both forward and backward directions. The acid, HA, can lose a proton to become its conjugate base, A⁻. The base, B, can accept a proton to become its conjugate acid, HB⁺. Most acid-base reactions are fast so that the components of the reaction are usually in dynamic equilibrium with each other.^[7]


Aqueous solutions


Acetic acid, a weak acid, donates a proton (hydrogen ion, highlighted in green) to water in an equilibrium reaction to give the acetate ion and the hydronium ion. Red: oxygen, black: carbon, white: hydrogen.

Consider the following acid–base reaction:


 

CH₃COOH + H₂O ⇌ CH₃COO⁻ + H₃O⁺


Acetic acid, CH₃COOH, is an acid because it donates a proton to water (H₂O) and becomes its conjugate base, the acetate ion (CH₃COO⁻). H₂O is a base because it accepts a proton from CH₃COOH and becomes its conjugate acid, the hydronium ion, (H₃O⁺).^[8]

The reverse of an acid-base reaction is also an acid-base reaction, between the conjugate acid of the base in the first reaction and the conjugate base of the acid. In the above example, acetate is the base of the reverse reaction and hydronium ion is the acid.


 

H₃O⁺ + CH₃COO⁻ ⇌ CH₃COOH + H₂O


The power of the Brønsted–Lowry theory is that, in contrast to Arrhenius theory, it does not require an acid to dissociate.


Amphoteric substances


The amphoteric nature of water

The essence of Brønsted–Lowry theory is that an acid only exists as such in relation to a base, and vice versa. Water is amphoteric as it can act as an acid or as a base. In the image shown at the right one molecule of H₂O acts as a base and gains H⁺ to become H₃O⁺while the other acts as an acid and loses H⁺ to become OH⁻.

Another example is furnished by substances like aluminium hydroxide, Al(OH)₃.


 

Al(OH)₃ + OH⁻ ⇌ Al(OH)−
4, acting as an acid

3H⁺ + Al(OH)₃ ⇌ 3H₂O + Al³⁺(aq), acting as a base

Non-aqueous solutions

The hydrogen ion, or hydronium ion, is a Brønsted–Lowry acid in aqueous solutions, and the hydroxide ion is a base, by virtue of the self-dissociation reaction


 

H₂O + H₂O ⇌ H₃O⁺ + OH⁻


An analogous reaction occurs in liquid ammonia


 

NH₃ + NH₃ ⇌ NH+
4 + NH−
2


Thus, the ammonium ion, NH+
4, plays the same role in liquid ammonia as does the hydronium ion in water and the amide ion, NH−
2, is analogous to the hydroxide ion. Ammonium salts behave as acids, and amides behave as bases.^[9]

Some non-aqueous solvents can behave as bases, that is, proton acceptors, in relation to Brønsted–Lowry acids.


 

HA + S ⇌ A⁻ + SH⁺


where S stands for a solvent molecule. The most important such solvents are dimethylsulfoxide, DMSO, and acetonitrile, CH₃CN, as these solvents has been widely used to measure the acid dissociation constants of organic molecules. Because DMSO is a stronger proton acceptor than H₂O the acid becomes a stronger acid in this solvent than in water.^[10] Indeed, many molecules behave as acids in non-aqueous solution that do not do so in aqueous solution. An extreme case occurs with carbon acids, where a proton is extracted from a C-H bond.

Some non-aqueous solvents can behave as acids. An acidic solvent will increase basicity of substances dissolved in it. For example, the compound CH₃COOH is known as acetic acid because of its acidic behaviour in water. However it behaves as a base in liquid hydrogen chloride, a much more acidic solvent.^[11]


 

HCl + CH₃COOH ⇌ Cl⁻ + CH
3C(OH)+
2

Comparison with Lewis acid–base theory

In the same year that Brønsted and Lowry published their theory, G. N. Lewis proposed an alternative theory of acid–base reactions. The Lewis theory is based on electronic structure. A Lewis base is defined as a compound that can donate an electron pair to a Lewis acid, a compound that can accept an electron pair.^[12][13] Lewis's proposal gives an explanation to the Brønsted–Lowry classification in terms of electronic structure.



HA + B: ⇌ A:⁻ + BH⁺


In this representation both the base, B, and the conjugate base, A⁻, are shown carrying a lone pair of electrons and the proton, which is a Lewis acid, is transferred between them.


Adduct of ammonia and boron trifluoride

Lewis later wrote in "To restrict the group of acids to those substances that contain hydrogen interferes as seriously with the systematic understanding of chemistry as would the restriction of the term oxidizing agent to substances containing oxygen."^[13] In Lewis theory an acid, A, and a base, B:, form an adduct, AB, in which the electron pair is used to form a dative covalent bond between A and B. This is illustrated with the formation of the adduct H₃N−BF₃ from ammonia and boron trifluoride, a reaction that cannot occur in aqueous solution because boron trifluoride reacts violently with water in a hydrolysis reaction.



BF₃ + 3H₂O → B(OH)₃ + 3HF

HF ⇌ H⁺ + F⁻


These reactions illustrate that BF₃ is an acid in both Lewis and Brønsted–Lowry classifications and emphasizes the consistency between both theories.^{[citation needed]}

Boric acid is recognized as a Lewis acid by virtue of the reaction



B(OH)₃ + H₂O ⇌ B(OH)−
4 + H⁺


In this case the acid does not dissociate, it is the base, H₂O that dissociates. A solution of B(OH)₃ is acidic because hydrogen ions are liberated in this reaction.

There is strong evidence that dilute aqueous solutions of ammonia contain negligible amounts of the ammonium ion



H₂O + NH₃ ⥇ OH⁻ + NH+
4


and that, when dissolved in water, ammonia functions as a Lewis base.^[14]


Comparison with the Lux-Flood theory

The reactions between certain oxides in non-aqueous media cannot be explained on the basis of Brønsted–Lowry theory. For example, the reaction


 

2MgO + SiO₂ → Mg₂SiO₄


does not fall within the scope of the Brønsted–Lowry definition of acids and bases. On the other hand, MgO is basic and SiO₂ is acidic in the Brønsted–Lowry sense, referring to mixtures in water.


 

2H⁺ + MgO(s) → Mg²⁺(aq) + 2H₂O

SiO₂(s) + 2H₂O → SiO4−
4 + 4H⁺ (≡ Si(OH)₄(aq))


Lux-Flood theory also classifies magnesium oxide as a base in non-aqueous circumstances. This classification is important in geochemistry. Minerals such as olivine, (Mg,Fe)SiO₄ are classed as ultramafic; olivine is a compound of a very basic oxide, MgO, with an acidic oxide, silica, SiO₂.

Clive James: Climate Alarmists Won’t Admit They Are Wrong

Date: 04/06/17
Clive James, The Australia
From:  https://www.thegwpf.com/clive-james-climate-alarmists-wont-admit-they-are-wrong/

When you tell people once too often that the missing extra heat is hiding in the ocean, they will switch over to watch Game of Thrones, where the dialogue is less ridiculous and all the threats come true. The proponents of man-made climate catastrophe asked us for so many leaps of faith that they were bound to run out of credibility in the end.

 Author Clive James at his home in London.

Now that they finally seem to be doing so, it could be a good time for those of us who have never been convinced by all those urgent warnings to start warning each other that we might be making a comparably senseless tactical error if we expect the elastic cause of the catastrophists, and all of its exponents, to go away in a hurry.

I speak as one who knows nothing about the mathematics involved in modelling non-linear systems. But I do know quite a lot about the mass media, and far too much about the abuse of language. So I feel qualified to advise against any triumphalist urge to compare the apparently imminent disintegration of the alarmist cause to the collapse of a house of cards. Devotees of that fond idea haven’t thought hard enough about their metaphor. A house of cards collapses only with a sigh, and when it has finished collapsing all the cards are still there.

Although the alarmists might finally have to face that they will not get much more of what they want on a policy level, they will surely, on the level of their own employment, go on wanting their salaries and prestige.

Illustration: Eric Lobbecke

To take a conspicuous if ludicrous case, Australian climate star Tim Flannery will probably not, of his own free will, shrink back to the position conferred by his original metier, as an expert on the extinction of the giant wombat. He is far more likely to go on being, and wishing to be, one of the mass media’s mobile oracles about climate. While that possibility continues, it will go on being danger­ous to stand between him and a television camera. If the giant wombat could have moved at that speed, it would still be with us.

The mere fact that few of Flannery’s predictions have ever come true need not be enough to discredit him, just as American professor Paul Ehrlich has been left untouched since he predicted that the world would soon run out of copper. In those days, when our current phase of the long discussion about man’s attack on nature was just beginning, he predicted mass death by extreme cold. Lately he predicts mass death by extreme heat. But he has always predicted mass death by extreme something.

Actually, a more illustrative starting point for the theme of the permanently imminent climatic apocalypse might be taken as August 3, 1971, when The Sydney Morning Herald announced that the Great Barrier Reef would be dead in six months.

After six months the reef had not died, but it has been going to die almost as soon as that ever since, making it a strangely durable emblem for all those who have wedded themselves to the notion of climate catastrophe.

The most exalted of all the world’s predictors of reef death, former US president Barack Obama, has still not seen the reef; but he promises to go there one day when it is well again.

In his acceptance speech at the 2008 Democratic convention, Obama said — and I truly wish that this were an inaccurate paraphrase — that people should vote for him if they wanted to stop the ocean rising. He got elected, and it didn’t rise.

The notion of a countdown or a tipping point is very dear to both wings of this deaf shouting match, and really is of small use to either. On the catastrophist wing, whose “narrative”, as they might put it, would so often seem to be a synthesised film script left over from the era of surround-sound disaster movies, there is always a countdown to the tipping point.

When the scientists are the main contributors to the script, the tipping point will be something like the forever forthcoming moment when the Gulf Stream turns upside down or the Antarctic ice sheet comes off its hinges, or any other extreme event which, although it persists in not happening, could happen sooner than we think. (Science correspondents who can write a phrase like “sooner than we think” seldom realise that they might have already lost you with the word “could”.)

When the politicians join in the writing, the dramatic language declines to the infantile. There are only 50 days (former British PM Gordon Brown) or 100 months (Prince Charles wearing his political hat) left for mankind to “do something” about “the greatest moral challenge … of our generation” (Kevin Rudd, before he arrived at the Copenhagen climate shindig in 2009).

When he left Copenhagen, Rudd scarcely mentioned the greatest moral challenge again. Perhaps he had deduced, from the confusion prevailing throughout the conference, that the chances of the world ever uniting its efforts to “do something” were very small. Whatever his motives for backing out of the climate chorus, his subsequent career was an early demonstration that to cease being a chorister would be no easy retreat because it would be a clear indication that everything you had said on the subject up to then had been said in either bad faith or ­ignorance. It would not be enough merely to fall silent. You would have to travel back in time, run for office in the Czech Republic ­instead of Australia, and call yourself Vaclav Klaus.

Australia, unlike Rudd, has a globally popular role in the ­climate movie because it looks the part.

Common reason might tell you that a country whose contribution to the world’s emissions is only 1.4 per cent can do very little about the biggest moral challenge even if it manages to reduce that contribution to zero; but your eyes tell you that Australia is burning up. On the classic alarmist principle of “just stick your head out of the window and look around you”, Australia always looks like Overwhelming Evidence that the alarmists must be right.

Climate Change: The Facts 2017 edited by Jennifer Marohasy

Even now that the global warming scare has completed its transformation into the climate change scare so that any kind of event at either end of the scale of temperature can qualify as a crisis, Australia remains the top area of interest, still up there ahead of even the melting North Pole, ­despite the Arctic’s miraculous ­capacity to go on producing ice in defiance of all instructions from Al Gore. A C-student to his marrow, and thus never quick to pick up any reading matter at all, Gore has evidently never seen the Life magazine photographs of America’s nuclear submarine Skate surfacing through the North Pole in 1959. The ice up there is often thin, and sometimes vanishes.

But it comes back, especially when some­one sufficiently illustrious confidently predicts that it will go away for good.

After 4.5 billion years of changing, the climate that made outback Australia ready for Baz Luhrmann’s viewfinder looked all set to end the world tomorrow. History has already forgotten that the schedule for one of the big drought sequences in his movie Australia was wrecked by rain, and certainly history will never be reminded by the mass media, which loves a picture that fits the story.

In this way, the polar bear balancing on the Photoshopped shrinking ice floe will always have a future in show business, and the cooling towers spilling steam will always be up there in the background of the TV picture.

The full 97 per cent of all satirists who dealt themselves out of the climate subject back at the start look like staying out of it until the end, even if they get satirised in their turn. One could blame them for their pusillanimity, but it would be useless, and perhaps unfair. Nobody will be able plausibly to call actress Emma Thompson dumb for spreading gloom and doom about the climate: she’s too clever and too creative. And anyway, she might be right. Cases like Leonardo DiCaprio and Cate Blanchett are rare enough to be called brave. Otherwise, the consensus of silence from the wits and thespians continues to be impressive.

If they did wish to speak up for scepticism, however, they wouldn’t find it easy when the people who run the big TV outlets forbid the wrong kind of humour.

On Saturday Night Live back there in 2007, Will Ferrell, brilliantly pretending to be George W. Bush, was allowed to get every word of the global warming message wrong but he wasn’t allowed to disbelieve it. Just as all branches of the modern media love a picture of something that might be part of the Overwhelming Evidence for climate change even if it is really a picture of something else, they all love a clock ticking down to zero, and if the clock never quite gets there then the motif can be exploited forever.

But the editors and producers must face the drawback of such perpetual excitement: it gets perpetually less exciting. Numbness sets in, and there is time to think after all. Some of the customers might even start asking where this language of rubber numbers has been heard before.

It was heard from Swift. In Gulliver’s Travels he populated his flying island of Laputa with scientists busily using rubber numbers to predict dire events. He called these scientists “projectors”. At the basis of all the predictions of the projectors was the prediction that the Earth was in danger from a Great Comet whose tail was “ten hundred thousand and fourteen” miles long. I should concede at this point that a sardonic parody is not necessarily pertinent just because it is funny; and that although it might be unlikely that the Earth will soon be threatened by man-made climate change, it might be less unlikely that the Earth will be threatened eventually by an asteroid, or let it be a Great Comet; after all, the Earth has been hit before.

That being said, however, we can note that Swift has got the language of artificial crisis exactly right, to the point that we might have trouble deciding whether he invented it or merely copied it from scientific voices surrounding him. James Hansen is a Swiftian figure. Blithely equating trains full of coal to trains full of people on their way to Auschwitz, the Columbia University climatologist is utterly unaware that he has not only turned the stomachs of the informed audience he was out to impress, he has lost their attention.

Paleoclimatologist Chris Turney, from the University of NSW, who led a ship full of climate change enthusiasts into the Antarctic to see how the ice was doing under the influence of climate change and found it was doing well enough to trap the ship, could have been invented by Swift. (Turney’s subsequent Guardian article, in which he explained how this embarrassment was due only to a quirk of the weather and had nothing to do with a possible mistake about the climate, was a Swiftian lampoon in all respects.)

Compulsorily retired now from the climate scene, Rajendra Pachauri, formerly chairman of the Intergovernmental Panel on Clim­ate Change, was a zany straight from Swift, by way of a Bollywood remake of The Party starring the local imitator of Peter Sellers; if Dr Johnson could have thought of Pachauri, Rasselas would be much more entertaining than it is. Finally, and supremely, Flannery could have been invented by Swift after 10 cups of coffee too many with Stella. He wanted to keep her laughing. Swift projected the projectors who now surround us.

They came out of the grant-hungry fringe of semi-science to infect the heart of the mass media, where a whole generation of commentators taught each other to speak and write a hyperbolic doom-language (“unprecedent­ed”, “irreversible”, et cetera), which you might have thought was sure to doom them in their turn. After all, nobody with an intact pair of ears really listens for long to anyone who talks about “the planet” or “carbon” or “climate denial” or “the science”. But for now — and it could be a long now — the advocates of drastic action are still armed with a theory that no fact doesn’t fit.

The theory has always been manifestly unfalsifiable, but there are few science pundits in the mass media who could tell Karl Popper from Mary Poppins. More startling than their ignorance, however, is their defiance of logic. You can just about see how a bunch of grant-dependent climate scientists might go on saying that there was never a Medieval Warm Period even after it has been pointed out to them that any old corpse dug up from the permafrost could never have been buried in it. But how can a bunch of supposedly enlightened writers go on saying that? Their answer, if pressed, is usually to say that the question is too elementary to be considered.

Alarmists have always profited from their insistence that climate change is such a complex issue that no “science denier” can have an opinion about it worth hearing. For most areas of science such an insistence would be true. But this particular area has a knack of raising questions that get more and more complicated in the absence of an answer to the elementary ones. One of those elementary questions is about how man-made carbon dioxide can be a driver of climate change if the global temperature has not gone up by much over the past 20 years but the amount of man-made carbon dioxide has. If we go on to ask a supplementary question — say, how could carbon dioxide raise temperature when the evidence of the ice cores indicates that temperature has always raised carbon dioxide — we will be given complicated answers, but we still haven’t had an answer to the first question, except for the suggestion that the temperature, despite the observations, really has gone up, but that the extra heat is hiding in the ocean.

It is not necessarily science denial to propose that this long professional habit of postponing an answer to the first and most elementary question is bizarre. American physicist Richard Feynman said that if a fact doesn’t fit the theory, the theory has to go. Feynman was a scientist. Einstein realised that the Michelson-Morley experiment hinted at a possible fact that might not fit Newton’s theory of celestial mechanics. Einstein was a scientist, too. Those of us who are not scientists, but who are sceptical about the validity of this whole issue — who suspect that the alleged problem might be less of a problem than is made out — have plenty of great scientific names to point to for exemplars, and it could even be said that we could point to the whole of science itself. Being resistant to the force of its own inertia is one of the things that science does.

When the climatologists upgraded their frame of certainty from global warming to climate change, the bet-hedging man­oeuvre was so blatant that some of the sceptics started predicting in their turn: the alarmist cause must surely now collapse, like a house of cards. A tipping point had been reached.

Unfortunately for the cause of rational critical inquiry, the campaign for immediate action against climate doom reaches a tipping point every few minutes, because the observations, if not the calculations, never cease exposing it as a fantasy.

I myself, after I observed journalist Andrew Neil on BBC TV wiping the floor with the then secretary for energy and climate change Ed Davey, thought that the British government’s energy policy could not survive, and that the mad work that had begun with the 2008 Climate Change Act of Labour’s Ed Miliband must now surely begin to come undone. Neil’s well-inform­ed list of questions had been a tipping point. But it changed nothing in the short term. It didn’t even change the BBC, which continued uninterrupted with its determination that the alarmist view should not be questioned.

How did the upmarket mass media get themselves into such a condition of servility? One is reminded of that fine old historian George Grote when he said that he had taken his A History of Greece only to the point where the Greeks failed to realise they were slaves. The BBC’s monotonous plugging of the climate theme in its science documentaries is too obvious to need remarking, but it’s what the science programs never say that really does the damage.

Even the news programs get “smoothed” to ensure that nothing interferes with the constant business of protecting the climate change theme’s dogmatic status.

To take a simple but telling example: when Sigmar Gabriel, Germany’s Vice-Chancellor and man in charge of the Energiewende (energy transition), talked rings around Greenpeace hecklers with nothing on their minds but renouncing coal, or told executives of the renewable energy companies that they could no longer take unlimited subsidies for granted, these instructive moments could be seen on German TV but were not excerpted and subtitled for British TV even briefly, despite Gabriel’s accomplishments as a natural TV star, and despite the fact he himself was no sceptic.

Wrong message: easier to leave him out. And if American climate scientist Judith Curry appears before a US Senate com­mittee and manages to defend her anti-alarmist position against concentrated harassment from a senator whose only qualification for the discussion is that he can impugn her integrity with a rhetorical contempt of which she is too polite to be capable? Leave it to YouTube. In this way, the BBC has spent 10 years unplugged from a vital part of the global intellectual discussion, with an increasing air of provincialism as the inevitable result. As the UK now begins the long process of exiting the EU, we can reflect that the departing nation’s most important broadcasting institution has been behaving, for several years, as if its true aim were to reproduce the thought control that prevailed in the Soviet Union.

As for the print media, it’s no mystery why the upmarket newspapers do an even more thorough job than the downmarket newspapers of suppressing any dissenting opinion on the climate.

In Britain, The Telegraph sensibly gives a column to the diligently sceptical Christopher Booker, and Matt Rid­ley has recently been able to get a few rational articles into The Times, but a more usual arrangement is exemplified by my own newspaper, The Guardian, which entrusts all aspects of the subject to George Monbiot, who once informed his green readership that there was only one reason I could presume to disagree with him, and them: I was an old man, soon to be dead, and thus with no concern for the future of “the planet”.

I would have damned his impertinence, but it would have been like getting annoyed with a wheelbarrow full of freshly cut grass.

These byline names are stars committed to their opinion, but what’s missing from the posh press is the non-star name committed to the job of building a fact file and extracting a reasoned article from it. Further down the market, when The Daily Mail put its no-frills newshound David Rose on the case after Climategate, his admirable competence immediately got him labelled as a “climate change denier”: one of the first people to be awarded that badge of honour.

The other tactic used to discredit him was the standard one of calling his paper a disreputable publication. It might be — having been a victim of its prurience myself, I have no inclination to revere it — but it hasn’t forgotten what objective reporting is supposed to be. Most of the British papers have, and the reason is no mystery.

They can’t afford to remember. The print media, with notable exceptions, is on its way down the drain. With almost no personnel left to do the writing, the urge at editorial level is to give all the science stuff to one bloke. The print edition of The Independent bored its way out of business when its resident climate nag was allowed to write half the paper.

In its last year, when the doomwatch journalists were threatened by the climate industry with a newly revised consensus opinion that a mere 2C increase in world temperature might be not only acceptable but likely, The Independent’s chap retaliated by writing stories about how the real likelihood was an increase of 5C, and in a kind of frenzied crescendo he wrote a whole front page saying that the global temperature was “on track” for an increase of 6C. Not long after, the Indy’s print edition closed down.

At The New York Times, Andrew Revkin, star colour-piece writer on the climate beat, makes the whole subject no less predictable than his prose style: a cruel restriction.

In Australia, the Fairfax papers, which by now have almost as few writers as readers, reprint Revkin’s summaries as if they were the voice of authority, and will probably go on doing so until the waters close overhead. On the ABC, house science pundit Robyn Williams famously predicted that the rising of the waters “could” amount to 100m in the next century. But not even he predicted that it could happen next week. At The Sydney Morning Herald, it could happen next week. The only remaining journalists could look out of the window and see fish.

Bending its efforts to sensationalise the news on a scale previously unknown even in its scrappy history, the mass media has helped to consolidate a pernicious myth. But it could not have done this so thoroughly without the accident that it is the main source of information and opinion for people in the academic world and in the scientific institutions. Few of those people have been reading the sceptical blogs: they have no time. If I myself had not been so ill during the relevant time span, I might not have been reading it either, and might have remained confined within the misinformation system where any assertion of forthcoming disaster counts as evidence.

The effect of this mountainous accumulation of sanctified alarmism on the academic world is another subject. Some of the universities deserve to be closed down, but I expect they will muddle through, if only because the liberal spirit, when it regains its strength, is likely to be less vengeful than the dogmatists were when they ruled. Finding that the power of inertia blesses their security as once it blessed their influence, the enthusiasts might have the sense to throttle back on their certitude, huddle under the blanket cover provided by the concept of “post-normal science”, and wait in comfort to be forgotten.

As for the learned societies and professional institutions, it was never a puzzle that so many of them became instruments of obfuscation instead of enlightenment. Totalitarianism takes over a state at the moment when the ruling party is taken over by its secretariat; the tipping point is when Stalin, with his lists of names, offers to stay late after the meeting and take care of business.

The same vulnerability applies to any learned institution. Rule by bureaucracy favours mediocrity, and in no time at all you are in a world where the British Met Office’s (former) chief scientist Julia Slingo is a figure of authority and Curry is fighting to breathe.

On a smaller scale of influential prestige, Nicholas Stern lends the Royal Society the honour of his presence. For those of us who regard him as a vocalised stuffed shirt, it is no use saying that his confident pronouncements about the future are only those of an economist. Klaus was only an economist when he tried to remind us that Malthusian clairvoyance is invariably a harbinger of totalitarianism. But Klaus was a true figure of authority. Alas, true figures of authority are in short supply, and tend not to have much influence when they get to speak.

All too often, this is because they care more about science than about the media. As recently as 2015, after a full 10 years of nightly proof that this particular scientific dispute was a media event before it was anything, Freeman Dyson was persuaded to go on television. He was up there just long enough to say that the small proportion of carbon dioxide that was man-made could only add to the world’s supply of plant food. The world’s mass media outlets ignored the footage, mainly because they didn’t know who he was.

I might not have known either if I hadn’t spent, in these past few years, enough time in hospitals to have it proved to me on a personal basis that real science is as indispensable for modern medicine as cheap power. Among his many achievements, to none of which he has ever cared about drawing attention, Dyson designed the TRIGA reactor. The TRIGA ­ensures that the world’s hospitals get a reliable supply of isotopes.

Dyson served science. Except for the few holdouts who go on fighting to defend the objective ­nature of truth, most of the climate scientists who get famous are serving themselves.

There was a time when the journalists could have pointed out the difference, but now they have no idea. Instead, they are so celebrity-conscious that they would supply Flannery with a new clown suit if he wore out the one he is wearing now.

A bad era for science has been a worse one for the mass media, the field in which, despite the usual blunders and misjudgments, I was once proud to earn my living. But I have spent too much time, in these past few years, being ashamed of my profession: hence the note of anger which, I can now see, has crept into this essay even though I was determined to keep it out. As my retirement changed to illness and then to dotage, I would have preferred to sit back and write poems than to be known for taking a position in what is, despite the colossal scale of its foolish waste, a very petty quarrel.

But it was time to stand up and fight, if only because so many of the advocates, though they must know by now that they are professing a belief they no longer hold, will continue to profess it anyway.

Back in the day, when I was starting off in journalism — on The Sydney Morning Herald, as it happens — the one thing we all learned early from our veteran colleagues was never to improve the truth for the sake of the story. If they caught us doing so, it was the end of the world.

But here we are, and the world hasn’t ended after all. Though some governments might not yet have fully returned to the principle of evidence-based policy, most of them have learned to be wary of policy-based evidence. They have learned to spot it coming, not because the real virtues of critical inquiry have been well argued by scientists but because the false claims of abracadabra have been asserted too often by people who, though they might have started out as scientists of a kind, have found their true purpose in life as ideologists.

Modern history since World War II has shown us that it is unwise to predict what will happen to ideologists after their citadel of power has been brought low. It was feared that the remaining Nazis would fight on, as werewolves. Actually, only a few days had to pass before there were no Nazis to be found anywhere except in Argentina, boring one another to death at the world’s worst dinner parties.

After the collapse of the Soviet Union, on the other hand, when it was thought that no apologists for Marxist collectivism could possibly keep their credibility in the universities of the West, they not only failed to lose heart, they gained strength.

Some critics would say that the climate change fad itself is an offshoot of this ­lingering revolutionary animus against liberal democracy, and that the true purpose of the climatologists is to bring about a world government that will ensure what no less a philanthropist than Robert Mugabe calls “climate justice”, in which capitalism is replaced by something more altruistic.

I prefer to blame mankind’s inherent capacity for raising opportunism to a principle: the enabling condition for fascism in all its varieties, and often an imperative mindset among high-end frauds.[…]

This is an exclusive extract from the essay Mass Death Dies Hard by Clive James in Climate Change: The Facts 2017 edited by Jennifer Marohasy, published next month by the Institute of Public Affairs.