Atomic numbers (Z) are a special case of charge numbers, referring to the charge number of an atomic nucleus, as opposed to the net charge of an atom or ion.
All particles of ordinary matter have integer-value charge numbers, with the exception of quarks, which cannot exist in isolation under ordinary circumstances (the strong force keeps them bound into hadrons of integer charge numbers).
This means that the charge number for the ion is
A chemical charge can be found by using the periodic table.
An element's placement on the periodic table indicates whether its chemical charge is negative or positive.
A group in the periodic table is a term used to represent the vertical columns.
The noble gases of the periodic table do not have a charge because they are nonreactive.
Noble gases are considered stable since they contain the desired eight electrons.
When elements bond between positive and negative charged atoms, their charges will be switched and carried down on the other element to combine them equally.
Charge numbers also help to determine other aspects of chemistry.
A charge number also can help when drawing Lewis dot structures.
For an atomic nucleus, which can be regarded as an ion having stripped off all electrons, the charge number is identical with the atomic number Z, which corresponds to the number of protons in ordinary atomic nuclei.
Unlike in chemistry, subatomic particles with electric charges of two elementary charges (e.g. some delta baryons) are indicated with a superscript "++" or "−−".
For color-charged particles like quarks and hypothetical leptoquarks, the charge number is a multiple of 1/3.