P block: boron family

Question 1

valence shell electronic configuration~

Answer 1

ns2np1-6
B: [He]2s2 2p1
Al: [Ne]3s2 3p1
Ga: [Ar] 3d10 4s2 4p1 
In:[Kr]4d10 5s2 5p1
Th:[Xe]: 4f14 5d10 6s2 6p1

Question 2

atomic and ionic radii

Answer 2

increases down the group BUT size of Al>Ga, due to d orbital present in Ga(d has poor shielding effect)
And Th is barely larger than In (due to f orbital)

Question 3

Density

Answer 3

Ga»Al (d orbital)

Th»In (f)

Question 4

MP and BP

Answer 4

Decreases down the group but boron has exceptionally high MP due to very strong crystalline structure
Ga has exceptionally low MP and high boiling point. (due to dimer structure)

Question 5

Ionisation Enthalapy

Answer 5

decreases down the group but (IE)Ga > (IE)Al

and (IE)Th > (IE)In

Question 6

Electronegativity

Answer 6

Depends on atomic size, so should decrease down the group bUt there is marginal increase everytime down the group in grp 13
due to poor shielding effect of d and f electrons

Question 7

metallic charecter

Answer 7

increases down the group

Question 8

REDUCING PROPERTY

Answer 8

Till Al, reducing power increases but Ga onwards it decreases. Due to inert pair effect

Question 9

Oxidation states

Answer 9

B: +3, +1
Al: +3,+1
Ga: +3, +1
In: +3,+1
Th: +3,+1
BUT stability of +1 increases, from Ga on wards

Question 10

Nature off compunds

Answer 10

B: very small, very high IE => shares e-=> convalent bonds
Al: both covalent and ionic
ionic for the rest

Question 11

Reactions w air

Answer 11

B is amorphous form reacts w oxygen

2E + 3O2 -> 2E2O3
2E + 3N2 -> 2EN
Nature of oxides down the group turns more and more basic

B and Al only react w N2 at high temp to form nitrides, while the others dont.

Question 12

Reactions w base

Answer 12

Boron only reacts w alkali at high temp
2B+6KOH -> K3BO3 + 3H2
Al and Ga react w aqueous alkali and liberate H2:
2Al +2 NaOh + 6H2O -> 2Na+ [Al(OH)4]- + H2 (sodium tetrahydroxo aluminate ion)

2Ga + 2NaOh + 6H2O -> 2Na+[Ga(OH)4]- + 3H2

Question 13

Reaction w halogens

Answer 13

Forms triihalides
2E+3X2 -> 2EX3
f: ionic 
cl/B/I: covalent nature
boron trihalides are covalent in nature, soluble in organic solvent and bad conductor. SP2 hybridization, they act as lewis acid (due to tendency to accept electrons)
Lewis acid charecter: BF3

Question 14

Diagonal relation

Answer 14

• both non metal
  -high MP, BP and density
• form only covalent bond
  -exist in amorphous and crystalline state and exibhit allotropy
• have similar value of electronagtivity
  -hydrides are gaseous and inflammable
• carbides are very hard and used as abrasive
• halides vigorously hydrolyze
  oxides are acidic

Question 15

Reaction w acids

Question 16

Oxidising acids

Answer 16

nitric acid (HNO3)
perchloric acid (HCLO4)
chloric acid (HCLO3)
chromic acid (H2CrO4)
conc H2SO4

Question 17

Non Oxidising Acids

Answer 17

HCl
Hydroiodic acid HI
Hydrobromic acid (HBr)
hydrofluoric(HF)
 Phosphoric acid (H3PO4)
dil. H2SO4