← Periodic Table
17Cl35.450
Chlorine
Diatomic NonmetalChlorine is a chemical element with symbol Cl and atomic number 17. It also has a relative atomic mass of 35.5. Chlorine is in the halogen group (17) and is the second lightest halogen following fluorine.
Phase: GasAppearance: pale yellow-green gas
2, 8, 7
Physical Properties
Atomic Mass35.45 u
Density3.2 g/cm³
Melting Point171.6 K
Boiling Point239.11 K
Period3
PhaseGas
Chemical Properties
Electron Configuration1s2 2s2 2p6 3s2 3p5
Semantic Config[Ne] 3s2 3p5
Shells2, 8, 7
Electron Affinity348.575 kJ/mol
Electronegativity3.16
Ionization Energies
IE1: 1251.2 kJ/molIE2: 2298 kJ/molIE3: 3822 kJ/molIE4: 5158.6 kJ/molIE5: 6542 kJ/molIE6: 9362 kJ/molIE7: 11018 kJ/molIE8: 33604 kJ/molIE9: 38600 kJ/molIE10: 43961 kJ/molIE11: 51068 kJ/molIE12: 57119 kJ/molIE13: 63363 kJ/molIE14: 72341 kJ/molIE15: 78095 kJ/molIE16: 352994 kJ/molIE17: 380760 kJ/mol
Discovery
Discovered byCarl Wilhelm Scheele