The Structure of Chlorine
This is the structure of a chlorine molecule. Notice how the shared atoms are equidistant form the atoms. Therefor each atom has the same relationship to the shared atoms.
Chlorine is a member of the halogen family and group 17. It has seven valence electrons. It consists of 17 protons, 18 neutrons, and 17 electrons. Its electron configuration is the following:
1s2 2s2 2p6 3s2 3p5
Because the element has only seven electrons in its outer shell, the atom is unstable and will seek to find an element to combine with. All elements want to have 8 valence electrons.