What is the procedure to be followed while comparing bond angles and bond lengths ? I mean what should we check first, then second and so on.
Bond angles mainly depend on the following three factors:
- Hybridization: Bond angle depends on the state of hybridization of the central atom
Hybridization: sp3spX3, Bond angle: 109∘109∘, Example: CH4
Hybridization: sp2spX2, Bond angle: 120∘120∘, Example: BCl3
Hybridization: spsp, Bond angle: 180∘180∘, Example: BeCl2
Generally s- character increase in the hybrid bond, the bond angle increases.
- Lone pair repulsion: Bond angle is affected by the presence of lone pair of electrons at the central atom. A lone pair of electrons at the central atom always tries to repel the shared pair (bonded pair) of electrons. Due to this, the bonds are displaced slightly inside resulting in a decrease of bond angle.
- Electronegativity: If the electronegativity of the central atom decreases, bond angle decreases.
Bond length: is defined as the distance between the centers of two covalently bonded atoms. The length of the bond is determined by the number of bonded electrons (the bond order). The higher the bond order, the stronger the pull between the two atoms and the shorter the bond length. Generally, the length of the bond between two atoms is approximately the sum of the covalent radii of the two atoms. Bond length is reported in picometers. Therefore, bond length increases in the following order: triple bond < double bond < single bond.
Also check radius of peripheral and central metal to get electronegativity compare