ABSTRACT
Any crystal structure is represented by a basis of atoms centred on each lattice point, and it is clear that there are several repeating groups of atoms that look identical. There are several different ways in which atoms can bond together, but it is worth bearing in mind that descriptions of each of these types of bonding are only models of the true behaviour. Inside every atom, there is a positively charged nucleus and negatively charged electrons that can be considered to be orbiting around the nucleus in atomic shells. Ionic bonding involves the transfer of an electron from an electropositive element to an electronegative element, so is the bonding mechanism found in solids such as sodium chloride that are composed of metallic and nonmetallic elements. The attraction between these positive ions and the sea of negatively charged electrons forms the metallic bond which holds the solid together.
