When you hear the word “chlorine,” you probably think of swimming pools and their strange chemical smell.

It’s true that chlorine is used to kill germs and bacteria in swimming pools, but there is much more to learn about this element!

What is chlorine?

Chlorine is a greenish-yellow gas with a strong smell, very similar to bleach. The pure form of chlorine is poisonous to humans. Fortunately, chlorine can join with almost any other element.

When chlorine combines with another element, it forms what is called a chloride. Many of these chlorides are extremely important to life on Earth.

Chlorine is the 21st most abundant element in the Earth’s crust, the 3rd most abundant in our oceans, and the 9th most abundant in our bodies.

How was chlorine discovered?

In 1774, a Swedish pharmacist named Carl William Scheele accidentally separated chlorine from hydrochloric acid. However, Scheele thought the yellow-green gas he had discovered contained oxygen and was not its own separate element. He called what we know as chlorine by the name “muriaticum,” because hydrochloric acid was known as muriatic acid at the time.

It wasn’t until 1811 that an English chemist named Sir Humphry Davy found that there was no oxygen in chlorine gas, and that chlorine was its own element. Davy gave chlorine its name from the word “khloros,” which is Greek for yellow-green.

How do we use chlorine?

The human body uses chlorine to help fight germs, move muscles, and digest food. Animals also need chlorine to survive.

The same way that chlorine is used to kill bacteria in pools, it also helps keep drinking water clean and safe to drink. Not surprisingly, chlorine is also found in disinfectants, cleaning products, and bleach.

Billions of pounds of chlorine are produced in the United States every year for use in plastics, paper, paints, textiles, prescription medications, and more. Chlorine is one of the most important elements in the manufacturing and production of goods.

Chlorine is also used in several car products such as seat cushions and seat covers, as well as tire cords and bumpers. The use of chlorine in these products helps make cars lighter.

The super important condiment known as table salt also contains chlorine. The chemical name for salt is sodium chloride because it is a combination of the elements sodium and chlorine. Without chlorine, our food would taste bland and boring!

Chlorine Facts

-The liquid form of chlorine will burn the skin.

-During World War I, chlorine was actually used as a weapon to poison enemy soldiers.

-In its pure form, chlorine can cause trouble breathing and irritation of the eyes and skin.

-Chlorine belongs to a group of elements known as halogens or salt-forming elements.

-Some frogs have a chlorine compound in their skin that works as a painkiller.

-Chlorine gas is 2.5 times heavier than air.

-Chlorine is the second most common halogen on Earth.


-It is used to make chlorofluorocarbons (CFCs). These were used in air conditioners, hairsprays, and other products until CFCs started causing holes in the ozone layer, which protects humans from the sun. Now, CFCs are mostly banned.

-Leaking chlorine containers can be very dangerous. How do people know if a chlorine container is leaking? Ammonia reacts with chlorine to create a white mist, so it is used to detect these leaks.

-Humans can smell even very, very small amounts of chlorine.

-You will hardly ever find a chlorine element by itself in nature. It is usually either combined with another chlorine element or with other elements such as sodium.

For this reason, chlorine is considered a very “social” element.

Now you’re officially a chlorine expert! Not only is chlorine found in swimming pools, but it is also in the ocean, our bodies, most prescription medications, and more.