Chlorine (Cl)
The name chlorine comes from the Greek word chloros, meaning pale green, after the gas's yellow-green color.
Chlorine properties
- Atomic mass
- 35.45 u
- Category
- Halogen
- Group
- 17
- Period
- 3
- Block
- p-block
- Electronegativity
- 3.16
- Melting point
- 171.6 K (-101.5 °C)
- Boiling point
- 239.11 K (-34 °C)
- Density
- 3.214 g/L
- Oxidation states
- +7, +5, +1, −1
- Atomic radius
- 175 pm
- Ionization energy
- 12.968 eV
- Electron affinity
- 3.617 eV
- Radioactive
- No, has stable isotopes
- Discovered
- 1774
Chlorine electron configuration
- Electron configuration
- [Ne] 3s2 3p5
- Full electron configuration
- 1s2 2s2 2p6 3s2 3p5
- Electron shells
- 2 · 8 · 7
The electron configuration of Chlorine (Cl) is [Ne] 3s2 3p5. Its 17 electrons are arranged in shells as 2, 8, 7.
Protons, neutrons and electrons in Chlorine
A neutral Chlorine atom has 17 protons and 17 electrons. Most Chlorine atoms have about 18 neutrons: the atomic mass rounded to 35, minus the atomic number 17.
Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass
How many valence electrons does Chlorine have?
7
Chlorine has 7 valence electrons in its outermost shell, shell 3. These are the electrons involved in chemical bonding.
Chlorine orbital diagram
Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations
Molar mass of Chlorine
35.45 g/mol
One mole of Chlorine atoms (6.022 × 10²³ atoms) has a mass of 35.45 grams. Use this value to convert between grams and moles.
Compounds containing Chlorine
Chlorine facts
- The name chlorine comes from the Greek word chloros, meaning pale green, after the gas's yellow-green color.
- By mass, table salt (sodium chloride) is about 61% chlorine.
- Chlorine (Cl) has atomic number 17 and is a gas at room temperature. It was discovered in 1774.
Position in the periodic table
Chlorine is element 17, in period 3 and group 17 of the periodic table, in the p-block.
Uses of Chlorine
Chlorine is used to disinfect drinking water and swimming pools, which has greatly reduced diseases such as cholera and typhoid. Its largest industrial use is making PVC plastic for pipes, window frames and cable insulation. Chlorine is also used to produce household bleach, hydrochloric acid, solvents and many medicines and pesticides.
Who discovered Chlorine?
Swedish chemist Carl Wilhelm Scheele first made chlorine gas in 1774 by reacting hydrochloric acid with the mineral pyrolusite (manganese dioxide), but he thought it was a compound containing oxygen. Humphry Davy showed in 1810 that it is an element and gave it its name.
Where does the name come from?
Chlorine comes from the Greek chloros, meaning 'pale green' or 'yellowish green', the color of the gas. Humphry Davy proposed the name in 1810 after proving that the gas is an element.
Same group
Compare Chlorine
FAQ
What is the electron configuration of Chlorine?
The electron configuration of Chlorine (Cl) is [Ne] 3s2 3p5. Its 17 electrons are arranged in shells as 2, 8, 7.
How many protons, neutrons and electrons does Chlorine have?
A neutral Chlorine atom has 17 protons and 17 electrons. Most Chlorine atoms have about 18 neutrons: the atomic mass rounded to 35, minus the atomic number 17.
How many valence electrons does Chlorine have?
Chlorine has 7 valence electrons in its outermost shell, shell 3. These are the electrons involved in chemical bonding.
What is the molar mass of Chlorine?
The molar mass of Chlorine is 35.45 g/mol. This is the same number as its atomic mass, 35.45 u.
Is Chlorine a metal?
No. Chlorine is a halogen, so it is a nonmetal.
Is Chlorine radioactive?
Ordinary Chlorine is not radioactive: it has at least one stable isotope. Like every element, it also has radioactive isotopes, most of them made in laboratories.
Where is Chlorine on the periodic table?
Chlorine is element 17, in period 3 and group 17 of the periodic table, in the p-block.