The bond angles of the given species can be determined using VSEPR theory and hybridisation principles described in the sources:
- CO2: The central carbon atom undergoes sp hybridisation, resulting in a linear geometry with a bond angle of 180∘ .
- NH4+: The nitrogen atom is sp3 hybridised and forms four bond pairs with no lone pairs. This results in a regular tetrahedral geometry with a bond angle of 109.5∘ .
- NH3: The nitrogen atom is sp3 hybridised but has three bond pairs and one lone pair. According to the sources, lone pair-bond pair (lp-bp) repulsion is greater than bond pair-bond pair (bp-bp) repulsion, which reduces the ideal tetrahedral angle to 107∘ .
- H2O: The oxygen atom is sp3 hybridised with two bond pairs and two lone pairs. Because lone pair-lone pair (lp-lp) repulsion is even stronger than lp-bp repulsion, the bond angle is further reduced to 104.5∘ .
Comparing these values, the increasing order of bond angles is: H2O(104.5∘)<NH3(107∘)<NH4+(109.5∘)<CO2(180∘).