Question

Give reasons dioxygen is a gas while sulfur is a solid at room temperature.

Answer 1

Sulfur is a chemical element and it has atomic number $16$. It is a non-metal. It is one of the most reactive nonmetals in the periodic table of elements. Sulfur lies in the oxygen family in the periodic table. Oxygen has atomic number $8$.

Complete step by step solution:
Even though sulfur lies in the oxygen family, it behaves differently. Atomicity is the ability of an element to form bonds. So the atomicity of oxygen is two, i.e. it is diatomic. But sulfur is different from oxygen. Single bonds are preferred by sulfur atoms rather than the double bonds. Sulfur is larger than oxygen. Also, the van der Waals forces between them are very strong. While in oxygen, the intermolecular forces are very weak. The forces in them are van der Waal forces. This causes oxygen atoms to exist as a gas molecule. Moreover, sulfur exists as a puckered ring structure which is held by a strong single covalent bond. It is always found as a polyatomic molecule.
We know that generally covalent bonds are formed between two metals. Thus it can be concluded that the sulfur atom is solid and dioxygen is a gas at room temperature.

Additional information:
We know that the dioxygen molecule is very reactive. It must not be kept near combustible materials. Sulfur is a soft solid, which is odorless and has a yellow color.

Note: We can explain the state of oxygen and sulfur by referring to its melting point. The melting point of sulfur is more than that of room temperature. While oxygen exists as gas itself. Also double bonds are generally not found between sulfur atoms.