Basic Points of group 15 elements

1. GROUP 15 ELEMENTS
Nitrogen Family

2.  Group 15 or the Nitrogen
family Consist of :
 Nitrogen(N)
 Phosphorus(P)
 Arsenic(As)
 Antimony(Sb)
 Bismuth(Bi)

3. Group 15 consist of metal ,non-
metal and metalloids.
 Nitrogen(N) - non-metal
 Phosphorus(P) - non-metal
 Arsenic(As) - metalloid
 Antimony(Sb) - metalloid
 Bismuth(Bi) - metal

4.  Nitrogen comprises 78% by volume of
the atmosphere
Nitrogen also found in form of protein
in plants and animals.
Nitrogen found on earth’s crust occurs
as:
Sodium nitrate(Chile saltpetre)
Potassium nitrate(Indian saltpetre)
Prosperous is found in minerals of apatite
family.
Also essential mineral for living organism.

5. ELECTRONIC
CONFIGURATION
General electronic configuration
ns2np3.
Stability of +5 OS decreases as we
move down the group due to inert pair
effect.

6. ATOMIC RADII
 Nitrogen(N) 70
 Phosphorus(P) 110
 Arsenic(As) 121
 Antimony(Sb) 141
 Bismuth(Bi) 148
On moving down the group atomic
radius is expected to increase.
 As to Bi only a small increase in
radius is observed due to ineffective
shielding of filled d and/or f orbitals.

7. IONIZATION ENTHALPY
The ionization enthalpy values
decreases down the group due to
increase in size.
 Group 15 elements have higher
IE than group 14 and group16
due to stable half filled
configuration.

8. ELECTRONEGATIVITY
Down the group, electro negativity
decreases.
Nitrogen is most electronegative
element of the group .
Nitrogen forms Hydrogen bonds.

9. PHYSICAL PROPERTIES
 All the elements of this group are polyatomic. Except
nitrogen, all the elements show allotropy and catenation.
 Exception: N is diatomic as N-N is weak due to
interelectronic repulsion of lone pair .
 Metallic character increases down the group due to
decrease in ionization enthalpy and increase in atomic
size.
 N, P are non metals, As Sb metalloids and Bi metal.
 B.P. increases from top to bottom.
 M.P. increases up to arsenic and decreases for bismuth.

10. OXIDATION STATE
Show Oxidation State -3, +3 and +5 .
tendency to exhibit –3 oxidation state
decreases down the group due to increase in
size and metallic character.
The stability of +5 oxidation state decreases
and • that of +3 state increases (due to inert
pair effect) down the group. Bi only forms
BiF5 .
Nitrogen undergoes disproportion :
3HNO2 → HNO3 + H2O + 2NO

11. ANOMAL0US PROPERTY OF N
 Due to small size, high electronegativity, high IE and
non availability of d orbitals N2 is unreactive (inert)
due to strong pπ –pπ .
 Other elements of group do not form strong pπ –pπ
as their atomic orbitals are large and diffuse so they
cannot have effective overlapping .
 nitrogen cannot form dπ –pπ and dπ –dπ bond and
maximum covalency of 4 : due to non availability of d
orbitals Nitrogen cannot form R3P = O type
compounds, or R3P = CH2 (R = alkyl group).
Phosphorus, NCl5 not formed.

12. REACTIVITY TOWARDS
HYDROGEN
 Hydrides have formula EH3 •
 Bond dissociation enthalpy decreases down the group.
 Small size N overlaps better with H and overlap becomes
less effective with increase in size of atom.
 The stability of hydrides decreases from NH3 to BiH3 due
to decrease in bond dissociation enthalpy •
 The reducing character of the hydrides increases down the
group due to decrease in bond dissociation enthalpy.
 BiH3 is a strong reducing agent

13. REACTIVITY TOWARDS OXYGEN
Form oxides with formula E2O3 and
E2O5
The oxide in the higher oxidation
state of the element is more acidic
than that of lower oxidation state
Acidic character decreases down the
group because metallic character
increases .

14. REACTIVITY TOWARDS HALOGENS
Form Halides with formula EX3 and EX5.
Nitrogen does not form pentahalide due to non-
availability of the d orbitals in its valence shell.
Pentahalides are more covalent than trihalides.
All the trihalides of these elements except those
of nitrogen are stable. In case of nitrogen, only
NF3 is known to be stable
Trihalides except BiF3 are predominantly
covalent in nature.

15. REACTIVITY TOWARDS METAL
All element react with metal to
form binary compound.
With -3 oxidisation state.