Nitrogen (specifically, the common form N₂) is a non-polar molecule.
Understanding Polarity
Molecular polarity refers to how electrons are distributed within a molecule. It depends on two main factors:
- Electronegativity Difference: The difference in the ability of atoms to attract electrons in a bond. If there's a significant difference, the electrons are pulled more towards one atom, creating a partial negative charge near that atom and a partial positive charge near the other. This forms a polar bond.
- Molecular Geometry: The shape of the molecule determines if the effects of individual polar bonds cancel out or result in an overall dipole moment. Even with polar bonds, a symmetrical molecule can be non-polar if the bond dipoles cancel.
Polarity of Nitrogen (N₂)
The nitrogen molecule exists as a diatomic molecule, N₂, meaning two nitrogen atoms are bonded together. The bond between the two nitrogen atoms is a triple covalent bond (N≡N).
According to the reference provided:
- "Because this is a symmetrical molecule all the electrons are going to be shared equal between the two nitrogen atoms in fact they're the same atom."
This statement highlights the key reasons why N₂ is non-polar.
Why N₂ is Non-polar
Several factors contribute to the non-polar nature of the N₂ molecule:
- Identical Atoms: The molecule is formed from two identical nitrogen atoms. Both atoms have the same electronegativity.
- Equal Electron Sharing: Because the atoms are identical, the electrons in the covalent bond are shared equally between them. There is no difference in electron attraction between the two atoms.
- Symmetry: The N₂ molecule has a linear shape, and it is perfectly symmetrical. Since the electron distribution is equal and the molecule is symmetrical, there is no overall separation of charge (no dipole moment).
This equal sharing and symmetry mean that no part of the N₂ molecule has a significant partial positive or negative charge, classifying it as non-polar.
Comparing Polar and Non-polar Molecules
| Feature | Polar Molecule | Non-polar Molecule |
|---|---|---|
| Electron Sharing | Unequal | Equal |
| Electronegativity | Significant Difference | Little to No Difference |
| Charge Dist. | Uneven (partial charges) | Even (no partial charges) |
| Symmetry | Often asymmetrical | Often symmetrical |
| Example | Water (H₂O), HCl | Nitrogen (N₂), O₂, CO₂ |
Practical Implications
The polarity of a molecule influences its physical properties, such as its solubility. Non-polar molecules like nitrogen typically dissolve well in other non-polar substances (like oils or fats) but have limited solubility in polar substances like water.
In summary, the N₂ molecule is non-polar due to the equal sharing of electrons between the two identical nitrogen atoms and its symmetrical structure.
