Compare the shapes and bond angles of these oxynitrogen ions. NO2+ NO2- NO3- NO43-
The Correct Answer and Explanation is :
Let’s analyze the shapes and bond angles of the oxynitrogen ions: NO₂⁺, NO₂⁻, NO₃⁻, and NO₄³⁻.
- NO₂⁺ (Nitronium ion):
- Shape: Linear
- Bond Angle: 180°
- The NO₂⁺ ion has a linear shape with two oxygen atoms bonded to a central nitrogen atom. The nitrogen atom in NO₂⁺ is sp hybridized, and it has no lone pairs, which leads to the linear shape. The ion has a formal positive charge, which means it has lost an electron and the nitrogen atom is electron-deficient, making it more electropositive.
- NO₂⁻ (Nitrite ion):
- Shape: Bent (V-shaped)
- Bond Angle: ~120°
- The NO₂⁻ ion has a bent shape because the nitrogen atom is sp² hybridized, with one lone pair of electrons. There are two bonding regions (the two O-N bonds), and the lone pair repels the bonding electrons, resulting in a bond angle slightly less than 120°, creating a bent structure. The negative charge on the oxygen contributes to the distortion of the bond angle.
- NO₃⁻ (Nitrate ion):
- Shape: Trigonal planar
- Bond Angle: 120°
- The NO₃⁻ ion has a trigonal planar geometry with three oxygen atoms bonded to the central nitrogen atom. The nitrogen in NO₃⁻ is sp² hybridized with no lone pairs, leading to a bond angle of 120°. The negative charge is delocalized over the three oxygens through resonance, stabilizing the ion and giving it a planar shape.
- NO₄³⁻ (Tetrahydroxidodinitrogen ion):
- Shape: Tetrahedral
- Bond Angle: 109.5°
- NO₄³⁻ has a tetrahedral shape, with four oxygen atoms symmetrically bonded to the central nitrogen atom. The nitrogen in NO₄³⁻ is sp³ hybridized, and the electron pairs around the nitrogen atom create a symmetric, tetrahedral structure. The bond angles between the oxygen atoms are about 109.5°.
Conclusion:
- NO₂⁺ is linear (180°) because it has no lone pairs and minimal electron repulsion.
- NO₂⁻ is bent (slightly less than 120°) due to a lone pair on nitrogen.
- NO₃⁻ is trigonal planar (120°) due to resonance and no lone pairs on nitrogen.
- NO₄³⁻ is tetrahedral (109.5°) due to four bonding pairs and no lone pairs on nitrogen.
These variations arise from differences in hybridization, lone pairs, and resonance, which influence the shape and bond angles.