Daily answer writing · Wed, 4 Nov, 2026
Bent's rule: bond angles in CH₂F₂ and NF₃, and why F goes axial in PCl₃F₂
State Bent's rule. Use it to explain:
(a) in CH2F2 the F–C–F angle (about 108°) is smaller than the tetrahedral angle while the H–C–H angle is larger than 109.5°;
(b) the bond angle in NF3 (about 102°) is smaller than in NH3 (about 107°);
(c) in trigonal bipyramidal PCl3F2 both fluorine atoms occupy the axial positions.
Syllabus: Common to CSE Paper I, IFoS Paper I and Geo-Scientist Mains (inorganic/physical): hybridisation, VSEPR theory, bond angles and shapes of molecules.
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