chemistry aqa additional - structure and bonding

Structure and Bonding

An atom is made up of three parts: protons, neutrons and electrons. These are called sub-atomic particles.

The protons and neutrons are in the middle of the atom in the nucleus. The electrons are in shells round the outside of the atom. Most of the size of the atom is made up of the empty space between the nucleus and the electrons.

sub atomic particles                  mass                     charge

       electron              almost nothing(taken as 0)       -1

        proton                                1                           +1

       neutron                                1                       neutral 0

atomic mass (or mass number) = number of neutrons + number of protons

atomic number = number of protons (or number of electrons)

The electron shells go in layers and each layer can only hold a certain number of electrons. The pattern…