Question

Which of the following elements of the Boron Family is non-metallic in nature?

• A. Ga
• B. In
• C. Tl
• D. B

Answer 1

The correct option is D B

Boron is a typical non-metal, aluminium is a metal but shows many chemical similarities to boron, and gallium, indium, thallium and nihonium are almost exclusively metallic in character.

THEORY
Group 13 Elements-The Boron Family:
The electronic configuration is [noble gas] $n{s}^{2}n{p}^1$.
B is a typical non-metal, Al is metal but shows many chemical similarities to boron.
Ga, In, and Tl are almost exclusively metallic in character.
B is a rare element, occurs as $H_{3}B{O}_3$, $N{a}_2{B}_4{O}_7.10H_{2}O$, $N{a}_2{B}_4{O}_7.4H_{2}O$. It exists in two isotopic forms, ${}^{10}B$ and ${}^{11}B$.
Al is the most abundant metal and occurs as $A{l}_2{O}_3.2H_{2}O$ and $N{a}_{3}Al{F}_6$.
Electronic Configuration:
Valence shell electronic configuration: $n{s}^{2}n{p}^1$
Boron Nobel gas core
Aluminum Nobel gas core
Gallium Nobel gas core + 10 d-electrons
Indium Nobel gas core + 10 d-electrons
Thallium Nobel gas core + 10 d-electrons + 14 f-electrons
Physical Properties:

1. B is non-metallic in nature.
2. It is an extremely hard and black-coloured solid.
3. It exists in many allotropic forms.
4. B has an unusually high melting point due to very strong crystalline lattice.
5. The rest of the members are soft metals with low melting points and high electrical conductivities.
6. Ga which has a lower melting point (303K), could exist in a liquid state during summer.
7. The density of the elements increases down the group from boron to thallium.