Question

a) For the following molecule and ion AlCl3 and NH2 i. Draw the shape (showing the lone pair(s) and bond pair(s) of electrons) ii. State bond angle(s) iii. Give the overall polarity

Answer 1

Given molecule & Ion ⇒ AlCl₃ & (NH₂)⁻  .

Now we have to find find ⇒ Shape, Bond angle and Polarity .

The structure of AlCl₃ ⇒ Trigonal Planer & Hybridisation is SP₂.
The structure of NH₂⁻  ⇒  Bent , Also It has 2 Bond pair & 2 lone pair.

⇒(i) Refer to attachment for the diagram 
showing the lone pair & Bond pair of the electron.
(a) For AlCl₃  :- It doesn't have lone pair of electron and it is stable.
(b)For NH₃⁻    :- It has two lone pair and also unstable.


⇒(ii) Bond Angle :- 
(a)  AlCl₃ (Aluminium Trichloride) :-  As we know the structure of  AlCl₃ is Trigonal Planer, The Bond angle bonded with 3 Chlorine atoms is 120°. Each chlorine atoms are sharing 1 electron with Al for completing the valence shell.

(b) NH₂⁻ :- As the structure of NH₂⁻ is bent , Then the bond angle between two atoms is 104.5° .


⇒ (iii) Overall Polarity :-
(a) AlCl₃ :- We know the electronegativity of Aluminium is 1.61 and that of Chlorine is 3.16  . Thus electronegativity difference is 1.55 , This means that the shared pair of electron are tilted towards the chlorine atoms(Hence it Polar Compound). Thus a Dipole is created in which chlorine has the negative charge and Al has the positive . 

(b) NH₂⁻  :- The NH₂⁻ is a polar compound because it Tends to attract the electron towards itself . Therefore it creates a negative charge .



Hope it Helps.