20Ca40.078

Calcium (Ca) – element 20

Calcium is a chemical element with the symbol Ca and atomic number 20. It is a alkaline earth metal in group 2 (alkaline earth metals), period 4 of the periodic table (s-block), and is a solid at room temperature.

Calcium (Ca) has atomic number 20, atomic mass 40.078 u and electron configuration [Ar] 4s2.

Download periodic table PDFOpen interactive periodic table

Calcium facts

SymbolCa
Atomic number20
Atomic mass40.078 u (g/mol)
Categoryalkaline earth metal
Groupgroup 2 (alkaline earth metals)
Period4
Blocks-block
Phase at 20 °CSolid
Electron configuration1s2 2s2 2p6 3s2 3p6 4s2
Noble-gas notation[Ar] 4s2
Electrons per shell2, 8, 8, 2
Valence electrons2

Bohr model and shells

Ca

Calcium has 20 electrons in 4 shells: 2, 8, 8, 2. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.

Physical and atomic properties

Melting point1115 K (841.9 °C)
Boiling point1757 K (1483.8 °C)
Density1.55 g/cm³
Electronegativity (Pauling)1
Electron affinity2.37 kJ/mol
Ionization energies589.8, 1145.4, 4912.4 kJ/mol (1st, 2nd, 3rd)
Molar heat capacity25.929 J/(mol·K)
Discovered byHumphry Davy

Use the atomic mass in the molar mass calculator for any formula containing Ca.

Position in the periodic table

HydrogenHHeliumHeLithiumLiBerylliumBeBoronBCarbonCNitrogenNOxygenOFluorineFNeonNeSodiumNaMagnesiumMgAluminiumAlSiliconSiPhosphorusPSulfurSChlorineClArgonArPotassiumKCalciumCaScandiumScTitaniumTiVanadiumVChromiumCrManganeseMnIronFeCobaltCoNickelNiCopperCuZincZnGalliumGaGermaniumGeArsenicAsSeleniumSeBromineBrKryptonKrRubidiumRbStrontiumSrYttriumYZirconiumZrNiobiumNbMolybdenumMoTechnetiumTcRutheniumRuRhodiumRhPalladiumPdSilverAgCadmiumCdIndiumInTinSnAntimonySbTelluriumTeIodineIXenonXeCesiumCsBariumBaLanthanumLaCeriumCePraseodymiumPrNeodymiumNdPromethiumPmSamariumSmEuropiumEuGadoliniumGdTerbiumTbDysprosiumDyHolmiumHoErbiumErThuliumTmYtterbiumYbLutetiumLuHafniumHfTantalumTaTungstenWRheniumReOsmiumOsIridiumIrPlatinumPtGoldAuMercuryHgThalliumTlLeadPbBismuthBiPoloniumPoAstatineAtRadonRnFranciumFrRadiumRaActiniumAcThoriumThProtactiniumPaUraniumUNeptuniumNpPlutoniumPuAmericiumAmCuriumCmBerkeliumBkCaliforniumCfEinsteiniumEsFermiumFmMendeleviumMdNobeliumNoLawrenciumLrRutherfordiumRfDubniumDbSeaborgiumSgBohriumBhHassiumHsMeitneriumMtDarmstadtiumDsRoentgeniumRgCoperniciumCnNihoniumNhFleroviumFlMoscoviumMcLivermoriumLvTennessineTsOganessonOg

Tap any element to open its page.

Frequently asked questions

What is the atomic mass of calcium?

The atomic mass of calcium is 40.078 u, so one mole of calcium atoms weighs 40.078 g.

What is the electron configuration of calcium?

Calcium has 20 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s², or [Ar] 4s² in noble-gas notation. Electrons per shell: 2, 8, 8, 2.

How many valence electrons does calcium have?

Calcium has 2 valence electrons (group 2).

Is calcium a metal?

Yes. Calcium is a alkaline earth metal.

Where is calcium on the periodic table?

Calcium is in group 2 (alkaline earth metals), period 4, in the s-block.

Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.