1911: Atomic number - The book of science

Atomic number
Atomic parts
Z
Commentary

Atomic number

Ernest Rutherford realized
the nucleus of an atom
has a positive charge
to be measured in units
of the charge of an electron;
however, he guessed
it would be equal
to half the atomic weight,
which Antonius van den Broek
quickly corrected, claiming
the charge should be
exactly equal to its position
in the periodic table.
*
An element’s position
in the periodic table
is based on the number
of protons in its nucleus.
The number of neutrons
is not always equal
to the number of protons;
many elements have
multiple isotopes, each
with a different number
of neutrons but this
was not yet understood.

Atomic parts

Nucleus
containing protons and neutrons
Electrons
in atomic orbitals
Electromagnetic force
between protons and electrons
Nuclear force
between protons and neutrons
Magnetic force
is related to angular momentums
of its nucleus and electrons
and the spin of its electrons.

Z

Z for zahl
in German, “number”
is shorthand for “atomic number,”
also for impedance,
the third axis,
the end of a series,
Zoro,
and, repeated, sleep.

Dmitri Mendeleev tried to order the first periodic table according to ascending atomic weights; however, he had to place tellurium ahead of iodine, even though tellurium has the greater atomic weight, to better align the chemical properties of the two with the chemical properties of the elements above them. The modern periodic table is arranged by atomic number.

Francis William Aston discovered isotopes in 1922, and James Chadwick discovered the neutron in 1932.