Every chemical bonds that are formed results from the desires of atoms to achieve stability like the inert and nonreactive noble gases. By so doing, their outer shell electrons must be completely filled to attain an octet configuration like the noble gases with eight outermost electrons.
An atom of oxygen has six outer electrons. To complete its octet, it will require just two more electrons.
This desire will make it bond with another atom. In the vicinity of another oxygen atom, it will bond. The type of bond formed will be a covalent bond which results from each of the oxygen atom sharing two of their valence electrons.
The joint shared electrons will now be four electrons. This four electrons will make each of their octet complete and a covalent bond occurs.
B.They all have their valence electrons in the same type of subshell
Explanation:
The electron configurations of elements in the same group (column) of the periodic table have them in the same type of subshell.
But the subshells may be of different shells. Thus , the energies of them need not be the same.
For example , The Alkalai Metals are found in the first column of the periodic table Group IA. This set of elements all have valence electrons in only the '' orbital and because they are in the first column they all have configuration. i.e,