Chlorine (chemical symbol Cl) is a chemical element. Its atomic number (which is the number of protons in it) is 17, and its atomic mass is 35.45. It is part of the 7th column (halogens) on the periodic table of elements.
Quick Facts Pronunciation, Appearance ...
Chlorine, 00Cl |
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Pronunciation | (KLOR-een, -eyen) |
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Appearance | pale yellow-green gas |
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| [35.446, 35.457][1] |
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Group | group 17 (halogens) |
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Period | period 3 |
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Block | p-block |
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Electron configuration | [Ne] 3s2 3p5 |
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Electrons per shell | 2, 8, 7 |
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Phase at STP | gas |
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Melting point | 171.6 K (−101.5 °C, −150.7 °F) |
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Boiling point | 239.11 K (−34.04 °C, −29.27 °F) |
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Density (at STP) | 3.2 g/L |
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when liquid (at b.p.) | 1.5625 g/cm3[2] |
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Critical point | 416.9 K, 7.991 MPa |
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Heat of fusion | (Cl2) 6.406 kJ/mol |
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Heat of vaporization | (Cl2) 20.41 kJ/mol |
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Molar heat capacity | (Cl2) 33.949 J/(mol·K) |
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Vapor pressure
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
128 |
139 |
153 |
170 |
197 |
239 |
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Oxidation states | −1, 0, +1, +2, +3, +4, +5, +6, +7 (a strongly acidic oxide) |
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Electronegativity | Pauling scale: 3.16 |
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Ionization energies | - 1st: 1251.2 kJ/mol
- 2nd: 2298 kJ/mol
- 3rd: 3822 kJ/mol
- (more)
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Covalent radius | 102±4 pm |
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Van der Waals radius | 175 pm |
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Spectral lines of chlorine |
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Natural occurrence | primordial |
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Crystal structure | orthorhombic |
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Speed of sound | 206 m/s (gas, at 0 °C) |
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Thermal conductivity | 8.9×10−3 W/(m⋅K) |
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Electrical resistivity | >10 Ω⋅m (at 20 °C) |
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Magnetic ordering | diamagnetic[3] |
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Molar magnetic susceptibility | −40.5·10−6 cm3/mol[4] |
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CAS Number | (Cl2) 7782-50-5 |
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Discovery and first isolation | Carl Wilhelm Scheele (1774) |
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Recognized as an element by | Humphry Davy (1808) |
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Category: Chlorine | references |
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