Flashcards for JEE Chemistry - p-Block Elements Class 12

 Page 1


p-Block Elements
Flash cards
Page 2


p-Block Elements
Flash cards
BORON FAMILY
Introduction
(a) The boron family consists of five elements :- Boron, aluminium, gallium, indium 
and thallium.
(b) Aluminum is third most abundant element found in earth crust (7.4%).
(c) All these elements have three electrons in the outermost orbit (ns
2
.np
1
)
Page 3


p-Block Elements
Flash cards
BORON FAMILY
Introduction
(a) The boron family consists of five elements :- Boron, aluminium, gallium, indium 
and thallium.
(b) Aluminum is third most abundant element found in earth crust (7.4%).
(c) All these elements have three electrons in the outermost orbit (ns
2
.np
1
)
Group properties (Continued)
All the group elements have similar physical and chemical properties due to same 
electronic configuration. Some of the properties of boron differ from other group 
element due to difference in its penultimate electronic configuration.
(s
2
, for boron, s
2
p
6
for Al) (s
2
p
6
d
10
for other three)
Page 4


p-Block Elements
Flash cards
BORON FAMILY
Introduction
(a) The boron family consists of five elements :- Boron, aluminium, gallium, indium 
and thallium.
(b) Aluminum is third most abundant element found in earth crust (7.4%).
(c) All these elements have three electrons in the outermost orbit (ns
2
.np
1
)
Group properties (Continued)
All the group elements have similar physical and chemical properties due to same 
electronic configuration. Some of the properties of boron differ from other group 
element due to difference in its penultimate electronic configuration.
(s
2
, for boron, s
2
p
6
for Al) (s
2
p
6
d
10
for other three)
Group properties (Continued)
(1) Physical properties
Note: – Boron is a semimetal, its crystalline form is hard, inert and poor 
conductor of electricity
(1.1) Oxidation state:
(a) These elements show +1 and +3 oxidation states ns
2
, np
1
.
(b) Boron shows only + 3 oxidation state. While other elements show + 1 and + 3 
oxidation state.
(c) + 1 oxidation state is more stable on moving down the group ( ?) due to inert 
pair effect.
(d) Ga shows +2 oxidation state in some compounds like GaCl
2
but actually this is 
a combination of Ga
1+
and Ga
3+
,
Ga
+
(GaCl
4
)
¯
? GaCl
2
.
Page 5


p-Block Elements
Flash cards
BORON FAMILY
Introduction
(a) The boron family consists of five elements :- Boron, aluminium, gallium, indium 
and thallium.
(b) Aluminum is third most abundant element found in earth crust (7.4%).
(c) All these elements have three electrons in the outermost orbit (ns
2
.np
1
)
Group properties (Continued)
All the group elements have similar physical and chemical properties due to same 
electronic configuration. Some of the properties of boron differ from other group 
element due to difference in its penultimate electronic configuration.
(s
2
, for boron, s
2
p
6
for Al) (s
2
p
6
d
10
for other three)
Group properties (Continued)
(1) Physical properties
Note: – Boron is a semimetal, its crystalline form is hard, inert and poor 
conductor of electricity
(1.1) Oxidation state:
(a) These elements show +1 and +3 oxidation states ns
2
, np
1
.
(b) Boron shows only + 3 oxidation state. While other elements show + 1 and + 3 
oxidation state.
(c) + 1 oxidation state is more stable on moving down the group ( ?) due to inert 
pair effect.
(d) Ga shows +2 oxidation state in some compounds like GaCl
2
but actually this is 
a combination of Ga
1+
and Ga
3+
,
Ga
+
(GaCl
4
)
¯
? GaCl
2
.
Group properties (Continued)
(1.2) Tendency to form ionic compounds :
(a) It increases from B to Tl.
(b) Ionization energy of boron is very high and it is not compensated by lattice as 
well as hydration energy in solution. So it forms only covalent compound.
(c) The high charge density (small size & high charge) of Al
3+
allows it to form both 
covalent and ionic compounds.
(d) Gallium forms ionic compounds except GaCl
2
.
(e) Thallium forms only ionic compounds.