Chlorine

17
Cl
Group
17
Period
3
Block
p
Protons
Electrons
Neutrons
17
17
18
General Properties
Atomic Number
17
Atomic Weight
35.453
Mass Number
35
Category
Halogens
Color
Yellow
Radioactive
No
From the Greek word chloro, greenish yellow
Crystal Structure
Base Centered Orthorhombic
History
Around 1630, chlorine was recognized as a gas by the Belgian chemist and physician Jan Baptist van Helmont.

Elemental chlorine was first prepared and studied in 1774 by Swedish chemist Carl Wilhelm Scheele.

By 1810, the scientific consensus was that chlorine was actually a compound that contained oxygen.

In 1811, Sir Humphry Davy concluded the new gas was in fact a new element.
Electrons per shell
2, 8, 7
Electron Configuration
[Ne] 3s2 3p5
Cl
Tree frogs have a chlorine compound in their skin that is a very powerful pain killer
Physical Properties
Phase
Gas
Density
0.003214 g/cm3
Melting Point
171.65 K | -101.5 °C | -150.7 °F
Boiling Point
239.11 K | -34.04 °C | -29.27 °F
Heat of Fusion
3.2 kJ/mol
Heat of Vaporization
10.2 kJ/mol
Specific Heat Capacity
0.479 J/g·K
Abundance in Earth's crust
0.017%
Abundance in Universe
0.0001%
Pure
Image Credits: Images-of-elements
Pure liquid chlorine under a pressure of 8 bars
CAS Number
7782-50-5
PubChem CID Number
24526
Atomic Properties
Atomic Radius
79 pm
Covalent Radius
102 pm
Electronegativity
3.16 (Pauling scale)
Ionization Potential
12.9676 eV
Atomic Volume
22.7 cm3/mol
Thermal Conductivity
0.000089 W/cm·K
Oxidation States
-1, 1, 2, 3, 4, 5, 6, 7
Applications
Chlorine is used for producing safe drinking water.

It is also extensively used in the production of paper products, dyestuffs, textiles, petroleum products, medicines, antiseptics, insecticides, food, solvents, paints, plastics, and many other consumer products.

Chlorinated compounds are used mostly for sanitation, pulp bleaching, disinfectants, and textile processing.
Elemental chlorine at high concentrations is extremely dangerous and poisonous
Isotopes
Stable Isotopes
35Cl, 37Cl
Unstable Isotopes
28Cl, 29Cl, 30Cl, 31Cl, 32Cl, 33Cl, 34Cl, 36Cl, 38Cl, 39Cl, 40Cl, 41Cl, 42Cl, 43Cl, 44Cl, 45Cl, 46Cl, 47Cl, 48Cl, 49Cl, 50Cl, 51Cl