Chlorine

Chlorine (Cl)

Halogen element. Poisonous greenish-yellow gas. Occurs widely in nature as sodium chloride in seawater. Reacts directly with many elements and compounds, strong oxidizing agent. Discovered by Karl Scheele in 1774. Humphrey David confirmed it as an element in 1810.
Atomic Number17
Atomic Weight35.45
Mass Number35
Group17
Period3
Blockp
Protons17 p+
Neutrons18 n0
Electrons17 e-
Chlorine liquid in an ampoule.jpg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
100 pm
Atomic Volume
Covalent Radius
99 pm
Metallic Radius
Ionic Radius
181 pm
Crystal Radius
167 pm
Van der Waals radius
175 pm
Density
0.002898 g/cm³
Boiling Point
238.6 K
Melting Point
172.2 K
Electrons per shell2, 8, 7
Electronegativity
3.16
Electrophilicity
3.6733159225832 eV/particle
Proton Affinity
513.6 kJ/mol
Electron Affinity
3.612725 eV/particle
Ionization Potential
12.96763 eV/particle
Heat of Vaporization
20.41 kJ/mol
Heat of Fusion
6.41 kJ/mol
Heat of Formation
121.302 kJ/mol
Molar Heat Capacity
33.949 J/(mol K)
Specific Heat Capacity
0.479 J/(g⋅K)
Thermal Conductivity
0.009 W/(m K)
Gas Basicity
490.1 kJ/mol
Dipole Polarizability
14.6 a₀
C6 Dispersion Coefficient
94.6 a₀
Oxidation States-1, 1, 2, 3, 4, 5, 6, 7
Color
Yellow
Crystal StructureBase Centered Orthorhombic (ORC)
Lattice Constant
6.24 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Ne] 3s2 3p5
Magnetic Ordering
Magnetic Susceptibility
PhaseGas
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryHalogens, Halogens
CAS GroupVIIB
IUPAC GroupVIIA
Glawe Number101
Mendeleev Number107
Pettifor Number99
Geochemical Classsemi-volatile
Goldschmidt Classlitophile
Radioactivity
RadioactiveNo
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
145 mg/kg
Abundance in Oceans
19,400 mg/L
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universe0.0001%

Isotopes of Chlorine

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

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. From the Greek word chloro, greenish yellow

DiscoverersCarl Wilhelm Scheele
Discovery LocationSweden
Discovery Year1774
Name OriginGreek: chlôros (greenish yellow).
Elemental chlorine at high concentrations is extremely dangerous and poisonous
Tree frogs have a chlorine compound in their skin that is a very powerful pain killer

Uses

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. Used in water purification, bleaches, acids and many, many other compounds such as chlorofluorocarbons (CFC).

Sources

Salt (sodium chloride, NaCl) is its most common compound. Commercial quantities are produced by electrolysis of aqueous sodium chloride (seawater or brine from salt mines).