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

Atomic Number:

Number of protons

Mass Number:

Number of protons + number of neutrons

Isotopes:

Isotopes are atoms with the same number of protons and electrons, however, they have a different number of neutrons. As shown in the diagram, the only difference between the isotopes is that there is a different amount of neutrons.

Relative Atomic Mass (Ar):

The mass of one atom is far too small to write out, so they are weighed in relativity to one hydrogen atom. e.g. an atom of Nitrogen (Ar of 14) is 14 times heavier than an atom of Hydrogen (Ar of 1)