Chemistry - Ionic Bonding

The Greeks first came up with the idea of the atom as being the smallest possible piece of matter. We now know that atoms are made from even smaller particles, arranged as a small central nucleus made from protons and neutrons surrounded by even smaller particles called electrons. The theory of atoms was not really taken seriously until the nineteenth century when a scientist called John Dalton was alive. Dalton suggested that each element is made of atoms of just one particular sort. He realized that the atoms of any element are different from the atoms of any other element. So in other words, iron contains a different type of atoms from those of oxygen, and the atoms in carbon are different from those of hydrogen. He also correctly recognized that compounds are made from different types of atom joined together.

Dalton worked out that during chemical reactions, the atoms in the chemicals at the start were simply rearranged to form the products. The original atoms are still there but joined up differently - but he was never able to explain how they did this. Dalton's theories took a long time to be accepted by other scientists since it was not possible to do the experiments needed to support his theories - atoms are too small to see.

Eventually, as scientists discovered more and more about the structure of atoms, they began to understand how they join together. It is all to do with the electrons which either transfer or are shared between atoms. When non-metals react together, they share electrons to form covalent bonds, but when a metal reacts with a non-metal, electrons transfer from one atom to another and this is called ionic bonding. In ionic bonding, metals always lose electrons forming positive ions whilst non-metals always gain them to form negative ions. The opposite charges attract and it is that attraction that is the ionic bond.