Covalent bonding is when two non-metals combine by sharing pairs of electrons. Both atoms feel they have a full outer shell. Each covalent bond provides one extra shared electron for each atom. Each atom has to make enough covalent bonds to fill its outer shell.
1. Hydrogen gas H2
Hydrogen atoms have only one electron so they need one more to complete the first shell so they often form single covalent bonds.
2. Chlorine gas Cl2
Each chlorine atom needs one more electron to complete outer shell so they form a single covalent bond…