Wikijunior:The Elements/Calcium
General:
editCalcium is a chemical element. Calcium is classified as an alkaline earth metal on the periodic table. The periodic table arranges chemical elements into periods (rows) and groups (columns). The element calcium is in period 4 and group 2 of the periodic table. Its atomic number is 20 and its symbol is Ca.
In addition to calcium, there are 5 other alkaline earth metals: beryllium, magnesium, strontium, barium, and radium
These elements share similar properties. They are shiny, silvery-white metals. They react with other elements to form useful compounds.
What does it look and feel like?
editCalcium is a soft, gray metal. When it burns, it burns with a yellowish-red flame. When it is exposed to air, it develops a gray-white coating because it reacts with the oxygen in the air to form a coating of calcium oxide (lime).
Strongly alkaline and reactive with any body fluids such as sweat, calcium metal burns flesh exposed to it. Do not touch it.
How was it discovered?
editCalcium has been known since Ancient Roman times. The Romans discovered a way to make calcium oxide by heating limestone in a furnace. However, it wasn't until 1808 that pure calcium was isolated by Sir Humphrey Davy. He combined calcium oxide (lime) with mercuric oxide and passed an electric current through the mixture. The result was pure calcium metal that was easy to separate from the mercury.
Where did its name come from?
editThe element calcium gets its name from the Latin terms calx or calcis, which refers to limestone. The element calcium was named by Sir Humphrey Davy the English chemist who discovered it in 1808.
Did You Know?
- As wet calcium hydroxide combines with air it becomes hard calcium carbonate. This chemical reaction is what causes cement to harden.
- Calcium is the most common metal in animals.
- Stalactites and stalagmites are made primarily of calcium carbonate.
Where is it found?
editCalcium is not found pure as an element due to its great tendency to react with other elements to form compounds, but it is commonly found in the compound calcium carbonate (CaCO3). Many rocks such as limestone, marble, chalk, and calcite contain this substance. Limestone caves are a great example of where calcium can be found. Seashells and snail shells are primarily calcium carbonate. Eggshells are mostly made from this compound too.
Calcium is the 5th most common element found in the Earth’s crust and in the oceans. Minerals that contain calcium bearing ores are typically found in sedimentary rock. In the United States calcium is found in Alabama, Alaska, Arizona, California, and Colorado. There are calcium mines in China, Europe, parts of Asia, and several African countries.
Calcium is also found in significant amounts in many foods. Dairy products like milk, yogurt and cheese contain calcium. Green vegetables also often have calcium. Broccoli, collard greens, almonds, sesame seeds, and beans all contain significant amounts of calcium.
What are its uses?
editCalcium is important for our body to run. It helps build strong bones and teeth, and it allows our muscles and brain cells work.
Calcium compounds are important for industry, construction, health, and agriculture.
In steelmaking, calcium oxide reacts with impurities to form “slag”. The impurities are removed with the slag, resulting in a purer metal.
Calcium is a main ingredient in cement and concrete. Romans used mortar made from a mixture of cement, lime, sand, and water to make strong buildings. They made plasters for artwork using calcium oxide, sand, and marble dust. Roman concrete was made from calcium oxide, volcanic ash, small stones, and water.
Calcium is an important substance in the building industry because calcium hydroxide (Ca(OH)2 is used in cement and mortar. Calcium carbonate is also used in plastics and adhesives as a filler. Because calcium oxide (CaO) neutralizes acid it can be used to decrease the effects of acid rain in rivers and lakes. Calcium is also commonly used in heartburn and antacid tablets. Calcium compounds are nearly everywhere in our bodies. In fact, calcium is an essential nutrient that is needed by the human body to help build strong bones and teeth.
In agriculture, calcium compounds are used to enrich soil for better crops. Calcium nitrate and calcium chloride are used as fertilizers. Calcium sulfate (gypsum) breaks down hard soil so water can get to plant roots.
Calcium is an essential nutrient for healthy soil and plant growth. It helps plants absorb sunlight to make energy for photosynthesis. Calcium adds strength and stability to plant parts. It helps to protect plants from disease and pests.
Is it dangerous?
editCalcium metal burns hot if ignited, and it reacts violently with water to form the strongly alkaline calcium hydroxide that can cause chemical burns.
Calcium compounds aren't dangerous unless they are strongly alkaline or acidic or if they are poisonous due to the other parts of the compound.
Elemental calcium can cause death if swallowed.
Calcium compounds in dietary supplements are generally safe.
Calcium compounds are nearly everywhere in our bodies. In fact, calcium is an essential nutrient that is needed by the human body to help build strong bones and teeth.
Calcium metal has a very high boiling/melting point.
References
editAZO Materials. (2023, October 1). Properties and applications of calcium (Ca). Reviewed by S. Baily, July 11. Updated by R. Davey. Retrieved from www.azo.com
Ducksters. (2024). Chemistry for Kids: Elements - Calcium. Retrieved from https://www.ducksters.com/science/chemistry/calcium.php
Hassani, N. (2023, August 16). How to add calcium to soil: using lime, bone meal, gypsum, and more. The Spruce. Reviewed by M. Leverette. Retrieved from www.thespruce.com
Kiddle Encyclopedia. (2023, October 16). Chemical compounds facts for kids. Retrieved from
https://kids.kiddle.co/Chemical_compound
Rung, R. (2023, November 3). Nutrition. W. Banks & C. Doka (Eds.), Medically reviewed by J. Jones. Healthline. Retrieved from https://www.healthline.com
USGS Science for a changing world. (n.d.) How do we extract minerals? Retrieved from How do we extract minerals? | U.S. Geological Survey
