15. Ionic Bonding

He is also credited with the discovery of cerium (Ce) and selenium (Se) and being the first to isolate silicon (Si) and thorium (Th).

which means that χ, as derived by Pauling, has implicit units of eV^½

His derived value of E^ion for the C-I bond also didn’t match the calculated value, but as that was inexplicably negative, Pauling wrote the discrepancy off as experimental error.

the energy change that results from adding an electron to an isolated atom.

In 1930, Mayer married Maria Goeppert, who was a student of Max Born’s. She won the Nobel Prize in Physics in 1963, becoming only the second woman to do so (the first was Marie Curie 60 years earlier).

Some older texts give this equation in cgs (Gaussian) units and so omit the Coulomb constant (4πε₀).

Lattice energy, ΔE, and lattice enthalpy, ΔH, are related but distinct concepts. Both are measures of the strength of the forces between the ions in an ionic solid. Specifically, lattice energy is the energy required to separate an ionic solid into gaseous ions. It is the heat given off or absorbed when a reaction is run at constant volume. Lattice enthalpy further takes into account that work must be performed against an outer pressure, P, such that ΔE = ΔH − PΔV, where ΔV is the change in volume. Enthalpy is the total energy of a system that can be converted into heat, and lattice enthalpy is the heat given off or absorbed when an ionic solid is separated into gaseous ions at constant pressure. Accordingly, the difference between ΔE and ΔH is small for reactions involving only liquids and solids because there is little if any change in volume during the reaction; however, the difference can be significant for reactions that involve gases and/or high pressures, especially if the reaction involves a change in the amount of gas. The sign of ΔH determines whether a reaction is exothermic (ΔH < 0) or endothermic (ΔH > 0).

These are the radii which multivalent ions would have if they were to retain their actual electron distributions but interact as if they were univalent. According to Pauling, r_univalent = r_multivalent Z^2/(n-1) where Z is the charge and n is the Born exponent.

There are actually two other polymorphs of TiO₂, namely anatase and brookite, but both are metastable in ambient conditions. There are another five high-pressure phases as well.

Experimental dipole moments are only available for molecular (gas phase) diatomic molecules.

If you have never seen two tipsy chemists settling this argument in a barroom brawl, then you’re not going to the right pubs.

Arnold Somerfield never won a Nobel Prize himself, although he was nominated no fewer than 81 times! He was also the doctoral advisor for at least six future Nobel laureates (including Pauling, Heisenberg, Pauli, Debye, Bethe, and Rabi) – more than anyone else in history.