Chem Unit 1

Topic 1.1: Atomic structure

Definitions (easy marks in the exam…so must learn!):

Atomic number (Z) of an element is the number of protons in the nucleus of its atom.

Mass number of an isotope is the number of protons + the number of neutrons in the nucleus.

Isotopes are atoms of the SAME element which have the SAME number of protons but different number of neutrons. (I.e. they have the same atomic number but different mass number)

Relative atomic mass (A_r) of an element is the average mass (taking into account the relative abundance of each isotope) of the atoms of that element relative to 1/12^th the mass…