What is Chlorine? | Types, Definition, Structure, Function & Facts
What is Chlorine?
Chlorine is the second element in the seventeenth column of the periodic table. It is classified as a member of the halogen group. It has 17 electrons and 17 protons with 7 valence electrons in its outer shell. It is the twentieth most abundant element in the earth’s crust.
Characteristics and Properties
Under normal conditions, chlorine is a gas that forms a diatomic molecule. This means that two chlorine atoms combine to form Cl2. Chlorine gas has a yellow-green color, a very strong odor (with bleach smell) and is toxic to humans. High concentrations of chlorine gas can be fatal.
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Chlorine is highly reactive and therefore does not exist in its free form in nature, but only in compounds with other elements. It will dissolve in water, but will also react with water as it dissolves. Chlorine will react with all other elements except noble gases.
The most common chlorinated compounds are called chlorides, but it also forms compounds with oxygen called chlorine oxides.
Highlights of Chlorine:
| Symbol | Cl |
| Atomic Number | 17 |
| Atomic Weight | 35.45 |
| Classification | Halogen |
| Phase at Room Temperature | Gas |
| Density | 3.2 g/L @ 0°C |
| Melting Point | 101.5°C, -150.7°F |
| Boiling Point | 34.04°C, -29.27°F |
| Discovered by | Carl Wilhelm Scheele produced the gas in 1774, but it was Sir Humphry Davy who first called it an element and named it chlorine in 1810 |
Where is Chlorine found on Earth?
Chlorine can be found in abundance in the earth’s crust and in seawater. In the ocean, chlorine is part of the compound sodium chloride (NaCl), also known as table salt. In the earth’s crust, the most common chlorinated minerals are halite (NaCl), carnalite, and sylvite (KCl).
How is Chlorine used today?
Chlorine is one of the most important chemicals used by industry. Tens of billions of pounds of chlorine are produced each year in the United States alone for use in industrial applications. It is used in the manufacture of various products, including pesticides, pharmaceuticals, cleaning products, textiles, and plastics.
You’ve probably heard people talk about using chlorine in swimming pools. Chlorine is used in swimming pools to keep them clean and safe by killing bacteria, germs, and algae. It is also used in drinking water to kill bacteria so that we don’t get sick when we drink it. Because it kills germs, chlorine is also used in disinfectants and is the basis of most bleaches.
How was Chlorine discovered?
Chlorine gas was first produced by Swedish chemist Carl Wilhelm Scheele in 1774. However, for many years scientists assumed that the gas contained oxygen. It was the British chemist Sir Humphry Davy who proved it to be a unique element in 1810. He also gave the element its name.
Where did Chlorine get its name?
Chlorine gets its name from the Greek word “chloros”, which means “yellow-green”.
Isotopes
Chlorine has two stable isotopes: Cl-35 and Cl-37. Chlorine present in nature is a mixture of these two isotopes.
Interesting Facts about Chlorine
Chlorine gas was used by the Germans during World War I to poison Allied soldiers.
About 1.9% of the ocean’s mass is made up of chlorine atoms.
It has a high density for gas of 3.21 grams per liter (air is about 1.29 grams per liter).
Chlorine is used to make chlorofluorocarbons or CFCs. CFCs were once widely used in air conditioners and aerosols. Unfortunately, they have contributed to the destruction of the ozone layer and have been largely banned.