Science, Tech, Math › Science Calcium Facts - Ca or Atomic Number 20 Chemical and Physical Properties of Calcium Share Flipboard Email Print Calcium is a metal. It readily oxidizes in air. Because it makes up such a large part of the skeleton, about one-third of the mass of human body comes from calcium, after water has been removed. Science Picture Co / Getty Images Science Chemistry Periodic Table Basics Chemical Laws Molecules Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated July 03, 2019 Calcium is silver to gray solid metal that develops a pale yellow tint. It is element atomic number 20 on the periodic table with the symbol Ca. Unlike most transition metals, calcium and its compounds exhibit a low toxicity. The element is essential for human nutrition. Take a look at calcium periodic table facts and learn about the element's history, uses, properties, and sources. Calcium Basic Facts Symbol: CaAtomic Number: 20Atomic Weight: 40.078Classification: Alkaline EarthCAS Number: 7440-701-2 Calcium Periodic Table Location Group: 2Period: 4Block: s Calcium Electron Configuration Short Form: [Ar]4s2Long Form: 1s22s22p63s23p64s2Shell Structure: 2 8 8 2 Calcium Discovery Discovery Date: 1808Discoverer: Sir Humphrey Davy [England]Name: Calcium derives its name from the Latin 'calcis' which was the word for lime (calcium oxide, CaO) and limestone (calcium carbonate, CaCO3)History: The Romans prepared lime in the first century, but the metal was not discovered until 1808. Swedish chemist Berzelius and Swedish court physician Pontin created an amalgam of calcium and mercury by electrolyzing lime and mercury oxide. Davy managed to isolate pure calcium metal from their amalgam. Calcium Physical Data State at room temperature (300 K): SolidAppearance: fairly hard, silvery white metalDensity: 1.55 g/ccSpecific Gravity: 1.55 (20 °C)Melting Point: 1115 KBoiling Point: 1757 KCritical Point: 2880 KHeat of Fusion: 8.54 kJ/molHeat of Vaporization: 154.7 kJ/molMolar Heat Capacity: 25.929 J/mol·KSpecific Heat: 0.647 J/g·K (at 20 °C) Calcium Atomic Data Oxidation States: +2 (most common), +1Electronegativity: 1.00Electron Affinity: 2.368 kJ/molAtomic Radius: 197 pmAtomic Volume: 29.9 cc/molIonic Radius: 99 (+2e)Covalent Radius: 174 pmVan der Waals Radius: 231 pmFirst Ionization Energy: 589.830 kJ/molSecond Ionization Energy: 1145.446 kJ/molThird Ionization Energy: 4912.364 kJ/mol Calcium Nuclear Data Number of Naturally Occurring Isotopes: 6Isotopes and % Abundance: 40Ca (96.941), 42Ca (0.647), 43Ca (0.135), 44Ca (2.086), 46Ca (0.004) and 48Ca (0.187) Calcium Crystal Data Lattice Structure: Face-Centered CubicLattice Constant: 5.580 ÅDebye Temperature: 230.00 K Calcium Uses Calcium is essential for human nutrition. Animals skeletons get their rigidity primarily from calcium phosphate. The eggs of birds and shells of mollusks are comprised of calcium carbonate. Calcium is also necessary for plant growth. Calcium is used as a reducing agent when preparing metals from their halogen and oxygen compounds; as a reagent in purification of inert gases; to fix atmospheric nitrogen; as a scavenger and decarbonizer in metallurgy; and for making alloys. Calcium compounds are used in making lime, bricks, cement, glass, paint, paper, sugar, glazes, as well as for many other uses. Miscellaneous Calcium Facts Calcium is the 5th most abundant element in the Earth's crust, making up 3.22% of the earth, air, and oceans.Calcium is not found free in nature, but calcium compounds are common. Some of the most common compounds found on Earth are limestone (calcium carbonate - CaCO3), gypsum (calcium sulfate - CaSO4·2H2O), fluorite (calcium fluoride - CaF2) and apatite (calcium fluorophosphate - CaFO3P or calcium chlorophosphate - CaClO3P)The top three countries that produce calcium are China, United States and India.Calcium is the main component of teeth and bones. However, too much calcium can lead to kidney stones or artery calcification.Calcium is the fifth most abundant element in the human body. Approximately one third of the mass of the human body is calcium after all water is removed.Calcium burns with a dark red color in a flame test.Calcium is used in fireworks to deepen the color. Calcium salts are used to produce orange in fireworks.Calcium metal is soft enough to cut with a knife, although somewhat harder than the metal lead.People and other animals can often taste the calcium ion. People report is as contributing a mineral, sour, or salty flavor.Calcium metal reacts exothermically with water or acid. Skin contact with calcium metal can cause irritation, corrosion, and chemical burns. Ingesting or inhaling calcium metal can be fatal due to the burns it can produce. Sources Hluchan, Stephen E.; Pomerantz, Kenneth (2006) "Calcium and Calcium Alloys". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH, doi:10.1002/14356007.a04_515.pub2Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.