Here's why:
* Diatomic nature: Nitrogen (N₂) and oxygen (O₂) exist as two atoms bonded together. This simple structure means they have a relatively small size and low molecular weight.
* Weak van der Waals forces: The only forces holding nitrogen and oxygen molecules together are weak, temporary attractions called van der Waals forces. These forces arise from temporary fluctuations in electron distribution, creating temporary dipoles. These dipoles are weak and easily broken, requiring little energy to separate the molecules.
Contrast with other substances:
Compare this to substances like water (H₂O), which has a much higher boiling point. Water molecules are held together by much stronger hydrogen bonds, a special type of dipole-dipole interaction. These strong bonds require significantly more energy to break, hence the higher boiling point.
Summary:
Nitrogen and oxygen have low boiling points due to their small size, low molecular weight, and the presence of weak van der Waals forces between their molecules.
