What's a difference between mercury and oxygen?

(They both are elements)

- - There are 80 protons in the nucleus of every atom of Mercury,

but only 8 of them in the nucleus of an atom of Oxygen.

- - Mercury must be warmer than 357°C in order to boil, but Oxygen

must only be warmer than - 183°C.

- - Mercury must be colder than - 39°C in order to freeze, but Oxygen

must be colder than - 219°C.

- - Oxygen is required for human life. Mercury is a deadly poison.