1.16 know what is meant by the terms atomic number, mass number, isotopes and relative atomic mass (Ar)

By Anonymous -
Atomic number - the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.

Mass number - the total number of protons and neutrons in a nucleus. The larger number shown on the periodic table. 

Isotopes - each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass.

Relative atomic mass (Ar) - the mass of an atom of a chemical element expressed in atomic mass units. It is approximately equivalent to the number of protons and neutrons in the atom (the mass number). 

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