Chemical element same atomic number, or number of protons. Nuclear scientists, however, define a pure element as one that consists of only one stable isotope. For example, a copper wire is 99.99% chemically pure if 99.99% of its atoms are copper, with 29 protons each. However it is not isotopically pure since ordinary copper consists of two stable isotopes, 69% Cu and 31% Cu, with different numbers of neutrons. However, a pure gold ingot would be both chemically and isotopically pure, since ordinary gold consists only of one isotope, Au. Atoms of chemically pure elements may bond to each other chemically in
Charge number 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 "−−". In chemistry, the same charge numbers are usually indicated as superscript "+2" or "−2". In particle physics, the charge number is a (derived) flavor quantum number. For color-charged particles like quarks and hypothetical leptoquarks, the charge number is a multiple of 1/3. Charge number Charge number ("z") refers to a