Bond angle

-終場ソ使者-

今日呀sir問我地
What is the bond angle of H₂O and NH₃?Why?
點解?我有考慮過好多因素,但都唔知點解-.-

-終場ソ使者-

H₂O
　O
/     \
H      H
中間隻角幾多度-.-
∠H-O-H
我知係104.5',不過唔知點解

-終場ソ使者-

我就係想知點計-.-

-終場ソ使者-

其實個principle我知,
In CH4 cause,
δ-俾個proton(form hydrogen)搶左,
bond pairs electrons之間既repulsive force細左
角度比較大
In NH3 cause,
δ-"還番"俾佢,bond pairs electrons既repulsive force大左
bond angle較細
唔知岩唔岩,自己諗
就係唔知點計-.-
YU兄,幫幫手[[tk_32]]

paladin

to be exact, you need mathematical model to calculate the lowest energy form of a certain molecule.
for the principle, the key is to consider the fact that bonding electron pair is less diffused than lone pair, and lone pair exerts greater replusive force than bonding pair, resulting in lesser bond angle in H2O than NH3, in turn, lesser than that in CH4.