13. Quantum Theory

Recall that polymorphs are structurally distinct forms of the same compound (same composition) and allotropes are polymorphs of an elemental substance.

A dielectric material is an electrical insulator that can be appreciably polarised by an applied electric field. Although credit for the term “dielectric” is often incorrectly given to William Whewell, it was probably first used by Michael Faraday, Lord Kelvin, or even Carl Gauss. In 1845, Michael Faraday discovered that the state of polarization of light passing through a piece of lead borosilicate glass could be changed by a magnet. The transparent bodies which he found displayed this property he first called ‘dimagnetics’ in analogy to dielectrics, but consulted his learned friend, William Whewell, for a second opinion. Whewell proposed altering the term to “dia-magnetic,” from the Greek “dia” meaning “through,” since the bodies through (dia) which electricity passes would have been called “diaelectric” but for the fact that “dielectric” was easier to pronounce.

Parmenides is also credited with the phrase “nothing comes from nothing”; but while the sentiment may have been there in his writing, the actual phrase ex nihilo nihil fit (from nothing nothing comes) first appeared in De Rerum Natura (On the Nature of Things) by the Roman Epicurean poet/philosopher Titus Lucretius Carus.

As of the time of printing, the Periodic Table lists 118 confirmed elements, all the way up to the noble gas oganesson (named after Russian/Armenian nuclear physicist Yuri Oganessian), only five or six atoms of which have ever been detected. It’s only one of two elements named after living scientists (you’ve probably never heard of the other one either – it’s seaborgium, named after the American nuclear chemist Glenn T. Seaborg, who co-discovered plutonium and several other transuranium elements plus more than 100 isotopes throughout the Periodic Table). The most recent additions at the time of printing (elements 113, 115, 117, and 118) were officially confirmed by IUPAC in December 2015.

Oddly, for Gilbert there was no electrical repulsion. Indeed, he even mentions the non-existence of repulsion as evidence of a distinction between magnetism and electricity.

All good science requires a level of exactness sometimes verging on the pedantic, so here’s a pedantic note on pronunciation for those of you who like that sort of thing: Principia is clearly a Latin word. Caesar would have said PrinKipia. If you’re discussing the work in an ecclesiastical setting (for some reason), the Church Latin PrinCHipia would be appropriate; but in normal English conversation, the title would follow English-language pronunciation rules (PrinSipia), just like the Latin PrinKipalis has become the English word prinSipal (principal). Basically, put pedantry aside and don’t get too hung up on pronunciation!

Dalton used the word “weight” rather than mass, and chemists have incorrectly called atomic masses “atomic weights” ever since.

The Greek “ιον” (ion) is the neutral present participle of “ιεναι” (ienai), meaning to go, thus, it is something which is going. The term was suggested to Faraday by his friend William Whewell in a letter dated 5 May 1834, to replace Faradays’ initial suggestions of “zetode” or “stechion.” Whewell also suggested the terms “anode” and “cathode” to Faraday. Although credit for the term “dielectric” is also often incorrectly given to William Whewell (Whewell did suggest the term “diamagnetic” in a letter to Faraday in 1845), it was probably first conceived by Michael Faraday himself, Lord Kelvin, or even Carl Gauss. In 1833, in response to a challenge by the poet S.T. Coleridge, Whewell invented the term “scientist.” Before this time, the only terms for this occupation in use were “natural philosopher” and “man of science”. He later coined the term “physicist” in 1840.

There is an impact crater (Davisson crater) named after him on the dark side of the moon. Prior to formal naming in 1970 by the International Astronomical Union, the crater was unimaginatively named Crater 377.

Even faculty at his own university viewed the work with skepticism due to the lack of any experimental evidence; and if not for the intervention and support of Albert Einstein, he might not have been awarded his PhD!

Alas, Max Knoll had died in 1969 or would surely have shared the prize.

In 1893, Pieter Zeeman (1865–1943) earned his PhD at Leiden, and in 1896, he disobeyed the direct orders of his supervisor, Heike Kamerlingh Onnes, and used laboratory equipment to measure the splitting of spectral lines by a strong magnetic field. He was fired for his efforts but was later vindicated when he won the 1902 Nobel Prize in Physics (shared with H.A. Lorentz, another of his PhD supervisors) for the discovery of what became known as the Zeeman effect. Onnes won his own Nobel 11 years later in 1913. With Zeeman’s work it became clear that atoms consisted of negatively charged oscillating particles which were just one-thousandth the mass of the hydrogen atom, and this conclusion was reached even before Thomson’s 1897 “discovery” of the electron.

In 1844, Michael Faraday used the term to refer to the “central point of an atom,” but the modern meaning was first proposed by Ernest Rutherford in 1912 [15].

The frequency ν in Hz is simply given by ν = ω₀/2π.

The naming of these shells is an historical accident. Between 1905 and 1910, Charles G. Barkla (1877–1944) discovered that elements emit characteristic x-ray radiation of two kinds, differing in their penetrating power. After having used the letters A and B, in 1911 he decided to assign K to the more penetrating and L to the less penetrating x-rays in order to leave other letters available for more penetrating radiation which he thought would be discovered. He soon found M and N radiation, but characteristic x-rays more penetrating than K were, of course, never discovered.

The multiplicity is equal to the number of unpaired electrons plus one, or 2S + 1, where S is the total spin angular momentum for all electrons (S =  ∑ m_s).

L =  ∑ m_ℓ

A Lewis acid is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base (any species that has a filled orbital containing an electron pair which is not involved with bonding).

He was knighted by Queen Victoria in 1866, becoming Sir William Thomson, and ennobled in 1892, becoming Baron Kelvin (addressed formally as The Right Honourable The Lord Kelvin of Largs or informally as simply Lord Kelvin).