List two things (number them 1 and 2) that are special about hydrogen allowing it to form hydrogen bonds when bound to oxygen: 1. 2. List two things (number them 3 and 4) that are special about oxygen allowing it to form hydrogen bonds when bound to hydrogen: 3. 4.

1. Presence of one valence electron in the outermost shell.

2. Less electronegative than Oxygen.

3. Six valence electrons its outer shell. So it needs to 2 electrons to get stable octet.

4. It is highly electronegative.

Explanation:

Hydrogen with the electronic configuration of 1s^1 needs 1 electron in its outer shell to be stable while oxygen with the electronic configuration of 1s^2 2s^2 2p^4 needs 2 electrons to complete octet state.

2 hydrogen atoms therefore bond covalently (sharing of electrons) with 1 Oxygen atom via hydrogen bond to form a water molecule.

This covalent hydrogen bond formed is polar as oxygen will attract electrons towards it due to high electronegativity.