* Covalent Bonding
* Ionic Bonding
* Metallic Bonding
Covalent Bonding:
This type of bonding simply consists of Atoms 'sharing' electrons. This results in the 'manufacture' of Molecules. Compounds made out of Molecules are called Molecular Compounds and generally have low melting and boiling points. This is because although the bonding between the atoms is strong, the bonding between the molecules is relatively weak and so a relatively low value of energy is required to split up the molecules so forming a liquid or gas.
Many compounds around us are molecular compounds - Alcohol, Ammonia, Water etc etc. You also find elements composed of molecules. In the case of Oxygen gas, the formula would be O2 because 2 atoms of Oxygen bond together and go around in pairs - this results in full outer shells of electrons and so both atoms feel 'happy'.
Ionic Bonding:
This type of bonding occurs in compounds such as Copper Sulphate, Sodium Chloride (Table Salt) etc. The basis of this type of bonding is that a giant 3d structure of ions (atoms which have lost or gained electrons) is formed.
e.g In the compound Sodium Chloride:
A piece of Sodium (if we forget about energy required to separate the individual atoms) is composed of Sodium atoms which each wish to lose an electron from their outer (valence) shell. Chlorine Gas is composed of Chlorine Molecules (which, again, if we forget about separating the individual atoms, is made up of Chlorine atoms). Each Chlorine atom wishes to gain an electron.
The solution? Each Sodium atom loses an electron from its valency shell and gives it to a Chlorine atom. Now each atom has full shells of electrons.
This swapping of electrons results in each sodium atom becoming a 1+ ion (lost 1 electron) and each Chlorine atom becoming a 1- ion (gained 1 electron). This difference in charges results in an attraction between the ions and from then on a giant 3d structure of these ions forms resulting in the creation of a crystal.
