P block: Carbon family

Question 1

Electronic configuration

Answer 1

ns2 np2
C:[he]2s2 2p2
Si: [Ne]3s2 3p2
Ge:[Ar]3d10 4s2 4p2
Sn:[Kr]4d10 5s2 5p2
Pb:[Xe]4f14 5d10 6s2 6p2

Question 2

atomic and ionic radii

Answer 2

increases down the group

Question 3

density

Answer 3

density increases down the group but (density)C> (Density)Si

Question 4

MP and BP

Answer 4

exception at MP for Tin (MP less than Pb) because electronegativity should increase down the group but after Si it is increasing due to shielding effect

Question 5

Metallic character

Answer 5

increases down the group

Question 6

oxidation state

Answer 6

+4, +2

stability goes from +4 to +2 down the group

Question 7

reducing properties

Answer 7

behave as both oxidising and reducing agent

Carbon is the strongest reducing agent: C>Si>Ge> Sn> Pb

Question 8

Catenation

Answer 8

decreases down the group

Question 9

Rxn w air

Answer 9

monooxides: Everyone excppt Si (SiO only at high temp)
CO: neutral, stong reducing agent
Ge/Sn/PbO: amphoteric

dioxides: 
CO2 acidic
SiO2acidic
GeO2less acidic
SnO2amphoteric
PbO2amphoteric

CO2+NaOh -> Na2CO3 + H2)
CO2+Ca(OH)2

Question 10

Rxn w water

Answer 10

C, Si, Ge-> not affected by water as bond dissociation energy of water as well as elements is very high
Sn reacts only w steam: Sn+2H2O -> SnO2+2H2
Pb is unaffected by water as as lead oxides form protective layer

Question 11

Reaction w halogens

Answer 11

c-. ONLY DIHALIDE: cx4

Rest make both- dihalide and tetrahalide: EX2, EX4
Tertrahalides: Covalent except SnF4, PbF4(which are ionic due to high electronegativity difference)

Dihalides: stability increases down the group

Question 12

Hydrolysis of halogens

Answer 12

• except CCL4, all other tetrahalides are easily hydrolysed by water astheiir central atom can accomodate the lone pair of electron from oxygen atom of water molecule in d orbital

Question 13

Importance of carbon

Answer 13

• exhibits catenation
• abundant in human body as well as 7th most abundant element in earth’s crust
• only s and p orbitals are involved, only upto 4 bonds.

Question 14

Allotropes: Graphite

Answer 14

layers, connected by weak vanderwalls forces

• hexagonal rings of carbon
• 3 carbon atoms forming sigma bonds
• easy to cleave between the layers so graphite is soft and slippery and can be used as a dry lubricant in machines
• good conductor of electricity

Question 15

Alloptropes: Diamond

Answer 15

• sp3 hybridisation
• tetrahedral shape
• hardest substance known on earth
• tungsten fillament used
• graphit can be turned into diamond at very high temp and pressure

Question 16

Allotropes: Fullerene

Answer 16

• newly discovered (1985)
• only pure form o carbon (no danglind bonds)
• buckminsterfullere
• 20, 6-membered ringsa nd 12, 5 memebered rings
• sp2 hybri
• each carbon forms 3 sigma bonds w 3 other carbon atoms
• 60 vertices and each is ocupied by one carbon atom. It contains both single and double bonds, with C-C distances of 143.5pm and 138.3pm resp. {Double bond- between two hexagon}