Question

BeF₂ is linear while SF₂ is angular through both are triatomic?

Answer 1

BeF₂ ∶ ₄Be = 2,2 = 1s² , 2s²

Be has 2 valence electrons. These two electrons are used to form bonds with two fluorine atoms So, it contains two bps but no lp. 

The structure of BeF₂ is shown as below:

F − Be − F

So, its shape is linear.

SF₂ : ₁₆S = 2,8,6

= 1s² , 2s²2p⁶ ,3s²3p⁴

S has 6 valence electrons. Out of these, two valence electrons are used to form bonds with two F-atoms So, it contains two bps and two Ips. 

The structure of SF₂ is shown as below:

So, its shape is angular due to lp-Ip repulsion.