It is represented by the symbol “O” and atomic number is for oxygen.
It is a member of the periodic table's chalcogen group.
Gaseous nature of oxygen:
An intermolecular attraction force exists between the molecules of a substance, which dictates its state at different temperatures.
Weak intermolecular or Van der Waals forces hold the oxygen atoms together in .
As a result, overcoming these weak forces requires little energy, therefore oxygen has a low boiling point and hence, oxygen is a gas at ambient temperature.