Question

for the following molecule and ion ALCL3 and NH2,

1. draw the shape showing the ions pair [s] and bond pair [s] of electrons.
2.state bond angle [s]
3.give the overall polarity

Answer 1

We have : Aluminium Chloride (AlCl3) and Amide ion (NH2) (-).

1) Aluminum Chloride :
Molecular geometry : Trigonal Planar.
Structure : Three Bonds each Al-Cl.
No lone pairs on Al. (central atom)

Amide ion : (NH2 )(-1)
Molecular Geometry : Bent / Angular.

2)
In AlCl3,
Bond Angle between each bonds is 120° .

In Amide, (NH2) (-))
Bond angle between two bond pairs is 104.5°.

3) Polarity will be such that partial negative charge is more stable on more electrinegative atom and vice -versa.

=>Cl has partial negative charge as its mire electronegative than Al.
=>H has partial positive charge as its more electropositive.

Answer 2

Given molecule Here :- AlCl₃ & (NH₂)⁻ 

Now We have to find the shape,bond angle and polarity . Thus

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

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



⇒(ii) For 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 pair of 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 here . 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 . This creates a negative charge on the compound.



Hope it Helps..