P blocks Flashcards
1
Q
Metallic characteristics in Group 15
A
Nitrogen and phosphorus : Non metal
Arsenic Antimony : Metalloids
Bismuth : Metal
2
Q
Composition of Nitrogen in atmosphere
A
78%
3
Q
Electronic configuration of Group 15
A
ns2 np3
4
Q
Why are group 15 elements extra stable?
A
Due to presence of half filled p orbitals (np3)
5
Q
Atomic and Ionic radii trend in group 15
A
Increases down the group
6
Q
Considerable increase in covalent radius from N to P, but small increase from As to Bi
A
Due to presence of completely filled d or f orbitals in heavier members
7
Q
Anomality in Atomic radius trend in Group 15
A
Considerable increase from N to P but small increase from As to Bi
8
Q
Ionisation enthalpy trend in group 15
A
Decreases down the group
9
Q
Why does ionisation enthalpy decrease down the group 15?
A
Due to gradual increase in atomic size
10
Q
Ionisation enthalpy of group 15 is much greater than group 14
A
Due to extra stable half filled p
orbitals
11
Q
Electronegativity trend in group 15
A
Decreases down the group
12
Q
Physical state of Group 15
A
N2 is gas,
other all are solids
13
Q
Metallic character trend in group 15
A
Increases down the group
14
Q
Why is N and P non metals
As and Sb metalloids
Bi metal??
A
Due to decrease in ionisation enthalpy down the group and increased atomic size
15
Q
Boiling point and melting point trend in Group 15 with exception
A
Increases from top to bottom
Exception : Mp increases upto arsenic and then decreases upto Bismuth
16
Q
Which group 15 element does not show allotrophy?
A
Nitrogen
17
Q
Common Oxidation state of group 15
A
-3, +3, +5
18
Q
Tendency to exhibut -3 Oxidation state decreases down the group
A
Due to increase in size and Mettalic character
19
Q
Which element of Group 15 hardly shows -3 oxidation state
A
Bismuth
20
Q
The stability of +5 Oxidation state increases / decreases down the group?
A
Decreases
21
Q
Only well characterized Bi(V) compound?
A
BiF5
22
Q
Stability of +5 state decreases and +3 state increases down the group.
A
Due to Inert Pair Effect
23
Q
Oxidation states displayed by N when it reacts with O
A
+1, +2, +4
24
Q
Oxidation state of Phosphorus in oxoacids
A
+1, +4
25
What happens to Oxidation state of nitrogen from +1 to +4 in acid solution?
Disproportionates
26
In which solution does the oxidation state of +1 to +4 of N disproportionates?
Acid solution
27
What happens to Phosphorus in alkali and acid solution?
All Oxidation states disproportionates to +5 and -3 state
28
In which solution does the Oxidation state of Phosphorus disproportionates to -5 and +3 states?
Alkali and Acid
29
Which oxidation state of As, Sb, and Bu becomes increasingly more stable wrt disproportionation
+3
30
Nitrogen is restricted to maximum of __ Covalency
4
31
Why is Nitrogen restricted to Maximum of 4 covalency
Due to absence of d orbitals
| only four orbitals (s and 3 p) are available for bonding
32
Why does N differ from rest of the members of the group?
Small size
High Electronegativity
High ionization Enthalpy
Absence of d orbital
33
Why can Heavier members of group 15 not form pπ-pπ multiple bonds with itself?
As their atomic orbitals are large and diffuse and cannot have effective overlapping
34
Why does nitrogen exist as diatomic molecule with triple bond?
Due to its ability to form pπ-pπ multiple bonds
35
Bond Enthalpy of N is very high
Due to formation of Triple bond between the Nitrogen atoms of its molecule
36
Which bond does Bi form in its elemental state?
Metallic Bond
37
Single N-N bond is weaker than P-P bond
High interelectronic repulsion of the non bonding electrons
38
Catenation tendency is weaker in N
Due to weak single N-N bond
39
Nitrogen cannot form dπ-pπ bond
Due to absence of d orbitals
40
Group 15 Elements
```
Nitrogen (N)
Phosphorus(P)
Arsenic (As)
Antimony (Sb)
Bismuth (Bi)
```
41
Why does stability of Hydrides decrease from NH3 to BiH3
Due to Decreasing Bond dissosiation enthalpy between E-H bond
42
Reducing character of hydrides of group 15
Increases from NH3 to BiH3
43
Which is the stronger reducing agent : NH3 or BiH3?
BiH3
44
Basicity trend of Group 15 Hydides
Decreases from NH3 to BiH3
45
Reactivity of Group 15 Elements towards Oxygen
E2O3
| E2O5
46
Trend of Acidic Character of group 15 oxides
Decreases down the group
47
Reactivity towards Halogen of Group 15
EX3
| EX5
48
Which trihalide of N are stable
NF3 only
49
Reactivity of group 15 elements toward Hydrogen
They form hydrides of the type EH3
50
pH nature of E2O3 in group 15
N2O3 P2O3 : Acidic
As2O3 Sb2O3 : Amphoteric
Bi2O3 : Basic
51
Trihalides of group 15 : covalent or ionic (with exception)
Covalent except BiF3
52
Reactivity of group 15 towards metal
group 15 elements will show -3 oxidation state
53
PH3 has lower boiling point than NH3
Due to formation of H bond in NH3
54
Group 15 More covalent : pentahalide or trihalide? Why?
PentaHalide
higher covalency due to higher oxidation state
55
Which Oxide is more acidic? Higher oxidation state or lower oxidation stye?
Higher Oxidation Stae
56
What type of agent is NH3
Mild Reducing Agent
57
Stability of Hydrides of group 15
Stability decreases from NH3 to BiH3
58
Trend in Bond Dissociation Enthalpy of E-H bond in group 15 Hydrides
Decreases from NH3 to BiH3
59
Stability of triHalides in group 15
All trihalides are stable except those of N
60
Nitrogen Does not form Pentahalida
Due to Absence of d orbital
61
Strongest reducing agent among Group 15 hydrides
BiH3
62
How to obtain Very Pure Nitrogen?
Thermal Decomposition of Barium/Sodium Azide
Ba(N3)2 -> Ba + 3 N2
Na(N3)2
63
Properties of Nitrogen (N2)
Colourless
Odourless
Tasteless
Non-toxic gas
64
Stable Isotopes of N
N-14
| N-15
65
Solubility of N2 in water
Very low
66
B pt and F pt of N2
Low
67
N2 is inert in room temperature
Due to high bond enthalpy of N-N triple bond
68
Trend of Reactivity of N2 with temp
Increases rapidly with increase in temperature
69
Reactivity of N2 with metal, hydrogen and oxygen
It reacts with them at high temp
Metal : M3N
Hydrogen : NH3
Oxygen : NO ( N2 + O2 -> 2NO )
70
Use of N2
Production of NH3
Used where inert atmosphere is required
Liq. N2 used as refrigerant
In cryosurgery
71
Properties of Ammonia
Colorless
Pungent Odour
Highly Soluble in water
Weak Base
72
State of Ammonia in room temp
Gas
73
Why is the Mp and Bp of ammonia higher than expected (by its molecular mass)
Due to formation of H bond in Liquid and solid phase
74
Shape of ammonia
Trigonal Pyramidal with N at apex
75
Nature of aqueous solution of Ammonia (Acid, Base, Neutral)
Weakly Basic
76
Why is ammonia a base
Presence of a lone pair of e on N atom making it Lewis Base
77
N2O Physical appearance n nature
colorless
| Neutral
78
NO Physical appearance n nature
Colorless Neutral
79
N2O3 Physical appearance n nature
Blue solid
| Acidic
80
NO2 Physical appearance n nature
Brown Gas
| Acidic
81
N2O4 Physical appearance n nature
Colorless Solid/liquid
| Acidic
82
N2O5 Physical appearance n nature
Colorless Solid
| Acidic
83
Why does NO2 Dimerise
Due to presence of odd number of Valence electron (by making lewis dot structure it will be clear)
84
Covalence of N in N2O5
4
85
H2N2O2 name
HypoNitrous acid
86
Hyponitrous acid formula
H2N2O2
87
Nitrous acid formula
HNO2
88
Nitric acid formula
HNO3
89
Process to prepare Nitric acid (name)
Ostwald's Process
90
Concentration of Lab grade Nitric acid
68% by mass
91
How does HNO3 exist in gaseous state
HNO3 exists as a Planar Molecule in Gaseous Phase
92
Conc. HNO3 is oxidising or reducing agent??
Strong Oxidising agent
93
Why does some metals (such as Al and Cr) not dissolve in Nitric acid
Dueto the formation of passive film of oxide on the surface
94
Does conc HNO3 react with non metals??
Yes, it oxideses then to their corresponding acid (except C oxidising it to CO2)
I->HIO3
S-> H2SO4
P-> H3PO4
95
Allotropes of Phosphorus
White, Red and Black (α , β)
96
appearance of White Phosphorous
White waxy translucent solid
97
Is white phosphorus poisonous?
Yes
98
Solubility of White Phosphorus
Insoluble in water but soluble in CS2 (carbon disulphide)
99
Does White Phosphorus glow in dark? what is the phenomenon called ?
Yes, Chemiluminescence
100
Why is White phosphorus more reactive
Due to angular strain in P4 molecule
101
Angle in White phosphorous
60°
102
What happens to white phosphorus in air
It readily catches fire and gives white fumes of P4O10
103
Lusture of Red Phosphorus
Iron grey lusture
104
Properties of Red Phosphorus
Odourless
| Non poisonous
105
Solubility of Red Phosphorous
Insoluble in water as well as CS2 (Carbon Disulphide)
106
Which is more reactive? red or white phosphorous??
White
107
Does Red phosphorous show Chemiluminescence
No
108
Structure of White P
Discrete Tetrahedral P4 molecules
109
Shape of Red P
Polymeric chain of P4 tetrahedra
110
Reactivity Order of Phosphorous
White > Red > Black
111
Which phosphorous upon heating gives α - Black Phosphorous
Red P
112
Which P upon heating gives β-Black Phosphorous ?
White P
113
Why is impure Phosphine Immflamable
Due to presence of P2H4 or P4 vapours
114
Properties of Phosphine
Colorless
Rotten fish Odour
Highly Poisonous
115
What happens when PH3 comes in contact with oxidising agent
Explodes
116
Solubility of PH3 in water
Slightly soluble in water
117
Nature of PH3
weakly Basic
118
What happens to aq. PH3 in the presence of light
It decomposes to red P and H2
119
Bond angle of PH4+ ion is greater thn PH3
Due to lower bp-bp repulsion thn lp-bp repulsion
120
Properties of PCl3
Colorless oily liquid
121
Properties of PCl5
Yellowish white powder
122
Shape of PCl5 in gaseous and Liquid phase
Trigonal bipyramidal
123
Two axial bonds are longer than three equitorial bonds of PCl5 .. why?
The two axial bond pairs suffer more repulsion as compared to equatorial bond pairs
124
How does PCl5 exist in Solid state
As an Ionic Solid with [PCl4]+ [PCl6]- ions
125
Shpae of [PCl4]+
Tetrahedral
126
Shape of [PCl6]-
Octahedral
127
Why does PCl3 fume in moisture
PCl3 Hydrolyses in the presence of moisture giving fumes of HCl
128
What happens when PCl5 is heated
It decomposes to PCl3 and Cl2
129
Are all five bonds of PCl5 equivalent?
No, two axial bonds are longer thn three equatorial bonds
