Noble gas electron configurations
In 1916, W. Kossel and G.N. Lewis realised tht all the noble gases have a full outer shell with eight electrons, except for helium. They linked the chemical stability (they are so stable) to the electronic configuration. They then suggested that other elements were trying to achieve this state by losing one or two electrons when they react to form compounds. Also, it seems that lighter elements are able to achieve stability by reaching the helium configuration of two outer shell electrons.
Formation of Ions
Atoms of metal elements in Groups 1 and 2 of the Periodic Table have only one or two outer shell electrons. They are able to lose electrons in order to gain a full outer shell and become positively charged ions, also known as cations. Most non-metal atoms have more than three outer shell electrons. They are able to gain electrons to become negatively charged, also known as anions. One electron leads to an anion with a single negative charge. A second electron is repelled by this anion because their charges are the same, so making a doubly charged anion is much harder. Anions with a charge of 3- are unusual and anions with a 4+ charge are almost unknown.
When metals react with non-metals in a chemical reaction, ions are only formed if the overally energy change for the reaction is favourable.Electrons are transferred from the metal atoms to the non-metal atoms. This often gives the metal and nonn-metal a stable state like a noble gas. The cations and anions which are formed are…