Compare the element hydrogen with the alkali metal sodium.

Sodium has 10 more protons and 13 more neutrons than hydrogen (hydrogen actually has no neutrons at all, whereas sodium has the 13 just mentioned so does have some)
Sodium has 3 energy levels / shells which contain electrons, hydrogen has only 1.
When forming ions, both usually form 1+ ions.
Hydrogen is a gas whereas sodium is a solid metal at room temperature.
Both has 1 electron in their outermost energy level.
Hydrogen is usually found as a diatomic molecule (covalently bonded to 1 other hydrogen atom) whereas sodium does not do this.
Hydrogen's boiling point is less than 0, and below that of water. Sodium's boiling point is above 0, and above that of water.

The answer is 3,5g co