The covalency of nitrogen in HNO₃ (nitric acid) is 4.
Explanation:
Covalency refers to the number of covalent bonds formed by an atom.
Structure of HNO₃:
Nitric acid has the following bonding:
- Nitrogen is the central atom
- It is bonded to:
- One OH group (single bond)
- Two oxygen atoms:
- One with a double bond (N=O)
- One with a coordinate bond (N→O)
Counting Covalent Bonds:
- One single bond (N–O)
- One double bond (counts as 2 bonds)
- One coordinate bond (counts as 1 bond)
Total covalent bonds = 1 + 2 + 1 = 4
Key Insight:
- Even though nitrogen has 5 valence electrons, in HNO₃ it forms four covalent bonds
- The structure involves resonance, so bonding is delocalized
Conclusion:
Nitrogen shows a covalency of 4 in HNO₃, as it forms four covalent bonds with surrounding oxygen atoms.