Formation of Water Molecule:
H ( Z = 1 ) 1S1 (1)
O ( Z = 8 ) 1S2 , 2S2 , 2P4 (2, 6)
Water molecule (H2O) contains two atoms of hydrogen & one atom of oxygen. Each hydrogen atom is in short of 1 electron of complete its duplet & oxygen atom is in short of 2 electrons to complete its octet. In the formation of water molecule, oxygen atom completes its octet by sharing one electron each with two hydrogen atoms. Similarly, each hydrogen atom completes its duplet by sharing one electron with oxygen atom. Thus, two separate single co-valent bonds are formed between hydrogen & oxygen atoms.
Type of bonding: Single co-valent bonding.