P block - 13th group

Question 1

What are p block elements?

Answer 1

Elements which fill their last electrons to a p-subshell

Question 2

Common electron configuration of group 13

Answer 2

ns2 np1

Question 3

Valency of group 13

Answer 3

3

Question 4

Oxidation no. of group 13

Answer 4

+3

Question 5

How does the metallic character vary down the group 13?

Answer 5

Metallic character increases down the group

Question 6

Describe the metallic properties of B

Answer 6

it is a metalloid

Question 7

Describe the metallic properties of Al

Answer 7

It’s a metal w/ amphoteric properties

Question 8

Describe metallic properties of Ga, In, Tl

Answer 8

They’re metals

Question 9

Why does B have special properties

Answer 9

Due to its small size

Question 10

Describe the nature of most compounds of group 13

Answer 10

Covalent

Question 11

What’s the most abundant metal in the earth’s crust?

Answer 11

Al

Question 12

What’s the 3rd most abundant element in the earth’s crust?

Answer 12

Al

Question 13

Why is Al considered non-reactive with air?

Answer 13

Al is reactive, but when exposed to air, an oxide layer of Al2O3 is formed.

This layer masks the inner metal and it becomes resistant to further reactions with O2

Question 14

Write Al reactions with oxygen

Answer 14

Al + O2 —> Al2O3

Question 15

Write Al reactions with halogens

Answer 15

2Al + 3Cl2 –> 2AlCl3

Question 16

Write Al reactions with Nitrogen

Answer 16

Al + N2 —> AlN

Question 17

Why is Al similar to Be?

Answer 17

Both are amphoteric

Question 18

Write reactions of Al with acids

Answer 18

It gives salts and H2 gas with acids

Al + HCl –> AlCl3 + H2

Question 19

Write reactions of Al with bases

Answer 19

Al + OH- + H2O –> 2[Al(OH2)4]- + H2

Al + OH- + H2O –> 2 AlO2- + 3H2

Question 20

Describe the nature of the Al3+ aqueous solution

Answer 20

Al3+ ion in aqueous solution is expected to be [Al(OH2)6] or hexaaquaaluminum ion

But, hydrolysis of Al3+ produces pentaaquahydroxialuminum [Al(OH2)5(OH)]2+ and then tetraaquahydroxidoaluminum ion [Al(OH2)4(OH)2]+

[Al(OH2)6]3+ + H20 –>[Al(OH2)5(OH)]2+ + H3O+

[Al(OH2)5(OH)]2+ + H2O –> [Al(OH2)4(OH)2]+ + H3O+

Question 21

Describe reactions of adding OH- ions to aluminum ions

Answer 21

First, a gelatinous precipitate of aluminum hydroxide is produced

With excess OH- ions, it is converted to tetrahydroxidoaluminate complex ion

Al3+ + OH- —> Al(OH)3

Al(OH)3 + OH- —> Al(OH)4- / AlO2- + 2H20

Question 22

What are some electron deficient compounds produced by 13th group elements?

Answer 22

AlCl3
BCl3

Question 23

Why are 13th group electron deficient compounds called lewis acids?

Answer 23

They can accept loan pairs

Question 24

What are the dimers formed by B and Cl and why do they do it?

Answer 24

Al2Cl6

Both Al and B compounds form dimers in the gaseous phase to satisfy the octet rule

Question 25

How does aluminum hydroxide appear as?

Answer 25

A white, gelatinous precipitate