The molecule of chloromethane (CH₃Cl) consists of three elements, i.e. carbon (Z = 6), hydrogen (Z = 1) and chlorine (Z = 17). Carbon atom has four valence electrons (2, 4); hydrogen has one while chlorine has seven electrons in the valence shell (2, 8, 7). In order to complete its octet, carbon shares three valence electrons with three hydrogen atoms while one is shared with the electron of chlorine atom.

The structure of covalent molecule may be written as follows: