✔ 最佳答案
1.
hydrogen iodide REALLY does not obey octet rule.
iodine has eight electrons in outermost shell; everyone got it.
oh but please remember, hydrogen DOES NOT !!
H has 2 electrons, thus is duet / doublet. similar case is helium and lithium ion.
2.
P has 5 valence electrons.
if X obeys octet rule, then 3 electrons are involved in single bond-formation with Cl ; PCl3 is resulted.
3 bond-pairs and 1 lone pair, shape expected is trigonal pyramid (like :NH3) by VSEPR; bond angle expected (naively) would be109.5 degree.
if Y is a hypervalent compound, all 5 electrons forms P-Cl bond, it'd be PCl5 .
5 bond-pairs and no lone-pair, it'd be trigonal bipyramid. bond angle between axial & equatorial P-Cl is 90*, that between two equatorial P-Cl is 120*.
3.
like water, O in the molecule has 2 bond pairs (H-O, O-O) and 2 lone pairs. these 4 pairs would adopt tetrahedral arrangement, yielding V-shape among these 3 atoms.
bod angle of H-O-O would primarily be 109.5*, yet bond pair-lone pair repulsion is stronger than bp-bp repulsion. the bonds are "squeezed" together, yielding bond angle lower than expected.
(but still, there're some other factors affecting the bond angle in H2O2, quite advance level in inorganic chem....)
