Chemical reactions are driven by transfer or sharing of electrons between two or more atoms. To show a specie that is reactive, a sound knowledge of the distribution of electrons in the atom is necessary.
The electron dot structure shows only chemical symbol of the element surrounded by dots which represents the valence electrons.
The chemical symbol represents the nucleus and all electrons except the valence ones.
The dots arranged on the four sides are called lone pairs. Those that are unpaired are called odd electrons.
Chlorine has 7 valence electrons in its outermost shell.
It is made up of 3 lone pairs and 1 odd pair of electron.
The odd pair accounts for the reason why chlorine is very reactive.
It will only require just one electron to join the odd pair so as to complete the octet and be like the noble gases.
