Atomic Structure 1.11 understand the terms atomic number, mass number, isotopes and relative atomic mass (Ar )

Atomic number, mass number, isotopes and relative atomic mass

Atomic number= number of protons in the nucleus of an atom

Mass number= number of protons + number of neutrons in the nucleus of an atom

Isotopes are atoms that have the same atomic number but different  mass numbers. This is because they contain the same number of protons but different numbers of neutrons.

Relative atomic mass is calculated from the masses and relative abundances of all the isotopes of a particular element. It is usually given in the symbol Ar.