Single bonds

Each hydrogen contributes an electron. The 2 shared electrons form a single bond.

Each chlorine contributes an electron. The 2 shared electrons form a single bond. We do not show the 1s, 2s2p electrons

Hydrogen contributes an electron. Chlorine contributes an electron. The 2 shared electrons form a single bond. We do not show the 1s, 2s2p electrons of chlorine