Calcium

Calcium is a chemical element with the symbol Ca and atomic number 20. It is a reactive metal that changes when it touches air. Calcium is very common. It is the fifth most abundant element in the Earth’s crust and the third most common metal, after iron and aluminium. We find it in rocks like limestone as a compound called calcium carbonate. It is also in minerals such as gypsum, anhydrite, fluorite, and apatite.

People have used calcium compounds for thousands of years. The pure metal was first isolated in 1808 by Humphry Davy using a process called electrolysis. Today, calcium compounds are used in many ways. They are in foods and medicines for calcium supplementation. They are also used to make paper, cement, and soaps.

In our bodies, calcium is very important. It is the most abundant metal in the human body. It helps send messages between cells, allows nerves to release neurotransmitters, helps muscle cells to move, supports the work of many enzymes, and is needed for building strong bones.

Characteristics

Calcium is a soft, silvery metal that looks pale yellow. It has similar traits to other metals in its group, especially strontium and barium. Each calcium atom has 20 electrons, arranged in a pattern that lets it easily lose two electrons in reactions, forming a stable ion.

Calcium melts at 842°C and boils at 1494°C. It is softer than lead and can be cut with a knife, though it takes some effort. It does not conduct electricity as well as copper or aluminium, but it conducts better for its weight because it is light. Calcium reacts with water to make calcium hydroxide and hydrogen gas. It also reacts with oxygen and nitrogen in the air to form calcium oxide and calcium nitride. When burned, it makes these compounds too. Calcium hydroxide is a strong base, and calcium carbonate and calcium sulfate are common minerals.

History

Calcium compounds have been used for thousands of years. People did not know their chemical makeup until much later. For example, lime was used to build and make statues as far back as 7000 BC. The ancient Romans used lime mortars made from heating limestone.

The name “calcium” comes from the Latin word for lime. In 1808, scientists first isolated calcium metal using a process called electrolysis. This was an important step in learning about this element.

Occurrence and production

Calcium makes up about 3% of Earth's crust. It is the fifth most common element and the third most common metal. You can also find it on the lunar highlands.

On Earth, calcium is often found in rocks and minerals. Some of these are limestone, dolomite, marble, chalk, and corals. Other important calcium minerals are gypsum, anhydrite, fluorite, and apatite.

The biggest makers of calcium are China, Russia, and the United States. In Russia and China, they make calcium using electricity on melted calcium chloride. In the U.S. and Canada, calcium is made by mixing lime with aluminium at very high temperatures.

Applications

Calcium has many important uses. It helps make steel stronger by removing things like oxygen and sulfur. It is also used in special mixtures for batteries and in drain cleaners to clear blockages.

Calcium compounds are found in everyday items such as food, medicines, and toothpaste. They help give us important nutrients and do useful jobs, like making toothpaste foamy or helping medicines work better. Calcium supplements are important medicines all over the world.

Food sources

See also: Calcium supplement

Many foods have a lot of calcium. These include dairy products like milk, yogurt, and cheese. You can also get calcium from fish such as sardines and salmon. Other good sources are soy products, kale, and fortified breakfast cereals.

Health groups suggest limits for daily calcium intake to keep people healthy. These limits change depending on how old you are.

Biological and pathological role

Calcium is an important element our bodies need. The calcium ion helps our muscles, blood flow, and digestion work properly. It is also important for building strong bones and helps blood to clot. Our bodies carefully control calcium levels because it connects with many other substances, like proteins, to do its job.

Calcium can attach to different parts of proteins and other molecules, which helps it do many things in the body. It also connects with fats in cell membranes, helping hold certain proteins in place. Our bodies get calcium from food and supplements, and hormones help control how much calcium is in our blood. Not having enough calcium can weaken bones, while too much can cause health problems.

Safety

Metallic calcium

Calcium is a reactive metal. It can cause burns if it touches water or moisture on the skin. If swallowed, it can harm the mouth, throat, and stomach. It is best to be careful around this metal to avoid getting hurt.