Halogens (I)

1. Halogens and Interhalogens
Dr. Mithil Fal Desai
Shree Mallikarjun and Shri Chetan Manju Desai College Canacona
Goa

2. s
block
d block
p
block
Halogens
f block
Where are Halogens in periodic table?

3. Atomic
number
Halogen Symbol Electronic
configuration
9 Fluorine F [He]2s22p5
17 Chlorine Cl [Ne]3s23p5
35 Bromine Br [Ar] 3d104s24p5
53 Iodine I [Kr] 4d105s25p5
85 Astatine At [Xe] 4f145d106s26p5
Halogens

4. Halogen Electronic
configuration
Oxidation state
F [He]2s22p5 -1, 0
Cl [Ne]3s23p5 -1, 0, +1, +3, +4, +5, +6, +7
Br [Ar] 3d104s24p5 -1, 0, +1, +3, +4, +5, +6
I [Kr] 4d105s25p5 -1, 0, +1, +3, +5, +7
Oxidation state
Most common and stable oxidation state among halogen is -1
as after acquiring one electron they get their octet complete.

5. Halogen Abundance in
earth crust
(ppm)
Relative
abundance
(rank)
F 544 13th
Cl 126 20th
Br 2.5 47th (rare)
I 0.5 62th (rare)
Abundance

6. Halogen Covalent radii
(pm)
Ionic radii (X-)
(pm)
F 72 133
Cl 99 184
Br 114 196
I 133 220
Ionic and covalent radii
Decrease

7. Halogen First Ionisation
Energy (kJ/mol)
Electron
affinity
(kJ/mol)
F 1681 -333
Cl 1259 -349
Br 1143 -325
I 1009 -296
Ionisation energy and electron affinity
Decrease
Fluorine is smaller in size and most electronegative
element

8. Reaction
X-
(g) + nH2O(l) X-
(aq)
(kJ/mol)
F -513
Cl -370
Br -339
I -274
Hydration energy
Decrease
Smaller the size of anion more is the hydration energy

9. Reaction
X-
(g) + nH2O(l) X-
(aq)
(kJ/mol)
F -513
Cl -370
Br -339
I -274
Hydration energy
Decrease
Smaller the size of anion more is the hydration energy

10. Halogen
χp
F 4.0
Cl 3.0
Br 2.8
I 2.2
Electronegativity
Decrease
Electronegativity of H is 2.1, C is 2.5,
N is 3.0 and O is 3.5

11. van
der
Waal
force
of
interaction
increases
Molecule Boiling point
(°C)
Melting point
(°C)
F2 -219 -188
Cl2 -101 -34
Br2 -7 60
I2 114 185
Physical properties

12. Physical characterstics
Halogen (X) Property of X2
Fluorine (F) highly toxic, colorless gas, is the most reactive element
Chlorine (Cl) highly toxic gas, pale yellow-green color. Chlorine is a
very strong oxidizing agent
Bromine (Br) reddish-orange liquid, unpleasant, choking odor.
Iodine (I) Intensely colored solid with metallic luster. volatile,
sublimes when heated (form a violet-colored gas).
Astatine (At) Solid, radioactive

13. Half reaction E°(V)
F2 + 2e- 2F- +2.89
Cl2 + 2e- 2Cl- +1.36
Br2 + 2e- 2Br- +1.08
I2 + 2e- 2I- +0.62
Standard reduction Potential
Decrease
in
reduction
potential