![Portrait de Charles Janet vers 1925](https://upload.wikimedia.org/wikipedia/commons/e/ed/Portrait_de_Charles_Janet_vers_1925.jpg)
Charles Janet (; 15 June 1849 – 7 February 1932) was a French engineer, company director, inventor and biologist. He is also known for his innovative ''left-step'' presentation of the
periodic table of chemical elements.
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]
Life and work
Janet graduated from the École des Mines
École may refer to:
* an elementary school in the French educational stages normally followed by secondary education
Secondary education or post-primary education covers two phases on the International Standard Classification of Education scal ...
and worked for some years in munitions. He then married the daughter of the owner of a manufacturing company and worked for it for the rest of his life, finding time for research in various branches of science. His collection of 40,000 fossils and other specimens was unfortunately dispersed after his death.
His studies of the morphology of the head of ants, wasps and bees, and his micrographs were of remarkable quality. He also worked on plant biology and finally wrote a series of papers on evolution. He was a prolific inventor and designed much of his own equipment, including the formicarium
A formicarium or ant farm is a vivarium which is designed primarily for the study of ant colonies and how ants behave. Those who study ant behavior are known as myrmecologists.
History
The formicarium was invented by Charles Janet, a French ...
, in which an ant colony is made visible by being formed between two panes of glass. In 1927 he turned his attention to the periodic table and wrote a series of six articles in French, which were privately printed and never widely circulated. His only article in English was poorly edited and gave a confused idea of his thinking.
Chemical ideas
Janet started from the fact that the series of chemical elements is a continuous sequence, which he represented as a helix
A helix () is a shape like a corkscrew or spiral staircase. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helic ...
traced on the surfaces of four nested cylinders. By various geometrical transformations he derived several striking designs, one of which is his "left-step periodic table", in which hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
and helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...
are placed above lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid ...
and beryllium
Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form m ...
. It was only later that he realized that his arrangement agreed perfectly with quantum theory
Quantum theory may refer to:
Science
*Quantum mechanics, a major field of physics
*Old quantum theory, predating modern quantum mechanics
* Quantum field theory, an area of quantum mechanics that includes:
** Quantum electrodynamics
** Quantum ...
and the electronic structure of the atom. He placed the actinides under the lanthanides twenty years before Glenn Seaborg
Glenn Theodore Seaborg (; April 19, 1912February 25, 1999) was an American chemist whose involvement in the synthesis, discovery and investigation of ten transuranium elements earned him a share of the 1951 Nobel Prize in Chemistry. His work i ...
, and he continued the series to element 120.
Janet's table differs from the standard table in placing the s-block elements on the right, so that the subshells of the periodic table are arranged in the order , , , ''n''s, from left to right. There is then no need to interrupt the sequence or move the f block into a 'footnote'. He believed that no elements heavier than number 120 would be found, so he did not envisage a g block. In terms of atomic quantum numbers
In quantum physics and chemistry, quantum numbers describe values of conserved quantities in the dynamics of a quantum system. Quantum numbers correspond to eigenvalues of operators that commute with the Hamiltonian—quantities that can be k ...
, each row corresponds to one value of the sum where ''n'' is the principal quantum number
In quantum mechanics, the principal quantum number (symbolized ''n'') is one of four quantum numbers assigned to each electron in an atom to describe that electron's state. Its values are natural numbers (from 1) making it a discrete variable.
A ...
and ℓ the azimuthal quantum number
The azimuthal quantum number is a quantum number for an atomic orbital that determines its orbital angular momentum and describes the shape of the orbital. The azimuthal quantum number is the second of a set of quantum numbers that describe ...
. The table therefore corresponds to the Madelung rule
The aufbau principle , from the German ''Aufbauprinzip'' (building-up principle), also called the aufbau rule, states that in the ground state of an atom or ion, electrons fill subshells of the lowest available energy, then they fill subshells ...
, which states that atomic subshells are filled in the order of increasing values of . The philosopher of chemistry Eric Scerri
Eric R. Scerri is a chemist, writer and philosopher of science of Maltese origin. He is a lecturer at the University of California, Los Angeles; and the founder and editor-in-chief of '' Foundations of Chemistry'', an international peer reviewed ...
has written extensively in favor of Janet's left-step periodic table, and it is being increasingly discussed as a candidate for the optimal or most fundamental form of the periodic table.
Janet also envisaged an element zero
Neutronium (sometimes shortened to neutrium, also referred to as neutrite) is a hypothetical substance composed purely of neutrons. The word was coined by scientist Andreas von Antropoff in 1926 (before the 1932 discovery of the neutron) for the ...
whose 'atom' would consist of two neutron
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...
s, and he speculated that this would be the link to a mirror-image table of elements with negative atomic numbers – in effect anti-matter. He also conceived of heavy hydrogen
Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two stable isotopes of hydrogen (the other being protium, or hydrogen-1). The nucleus of a deuterium atom, called a deuteron, contains one proton and one n ...
(deuterium). He died just before the discovery of the neutron, the positron and heavy hydrogen.[
]
His work was championed most notably by Edward G. Mazurs.
Family
Charles Janet is better known than his brother, Armand Janet, also an engineer and entomologist. Armand Janet became renowned as a lepidopterist
Lepidopterology ()) is a branch of entomology concerning the scientific study of moths and the three superfamilies of butterflies. Someone who studies in this field is a lepidopterist or, archaically, an aurelian.
Origins
Post-Renaissance, t ...
and served as president of the Société entomologique de France
The Société entomologique de France, or French Entomological Society, is devoted to the study of insects. The society was founded in 1832 in Paris, France.
The society was created by eighteen Parisian entomologists on January 31, 1832. The first ...
in 1911. Armand Janet is also known as a caver and explorer and was one of the first to explore the Verdon Gorge
The Verdon Gorge (French: ''Gorges du Verdon'') is a river canyon located in the Provence-Alpes-Côte d'Azur region of Southeastern France. It is about 25 km (15.5 mi) long and up to 700 metres (0.4 mi) deep. It was formed by the ...
.
References and notes
External links
Biographie synthétique de Charles Janet
*Eric Scerri, 2020
''The Periodic Table: Its Story and Its Significance''
2nd edition, Oxford University Press, New York,
{{DEFAULTSORT:Janet, Charles
1932 deaths
1849 births
19th-century French chemists
French lepidopterists
People involved with the periodic table
19th-century French engineers
20th-century French engineers
20th-century chemists
19th-century French zoologists
20th-century French zoologists
19th-century biologists
20th-century biologists
French biologists
19th-century French inventors
20th-century French inventors