HC-O-H ere can water molecules hydrogen bond to the molecule above?

Nitrogen, oxygen and fluorine are the highly electronegative elements. When they are shared electrons to a hydrogen atom to form a covalent bond , the electrons of the covalent bond are tend towards the more electronegative atoms. This partially positively charged hydrogen atom forms a bond with the other electronegative atom. This bond is knownas hydrogen bond and is weaker than covalent bond.

For example, in HF molcule, the hydrogen bond exists between hydrogen atom of one molecule and fluorine atom of another molecule.

H₂O, NH₃ , ethanol , Methanol etc

Conditions for H-bonding :

1. H atom must be bonded  to high elctronegative atoms like N, F and O

2. Electronegative atoms must be smaller, then onle shared pair electrons attracted and dipole is formed