27.1. A http://www.ck12.org
atomic number
Is equal to the number of protons in its nucleus.atomic radius
The distance from an atom’s nucleus to the outermost orbital of electron.Aufbau Principle
States that as protons are added one by one to the nucleus of an atom to build up the elements, electrons are
similarly added to the atomic orbitals.Avogadro’s number
Defined as 6.022× 1023. It is a number used to describe amounts of atoms and molecules.A-Z notation
The composition of any atom can be illustrated with this shorthand notation.