Calcium occurs naturally as carbonate in limestone and as silicate in many rocks and is reactive and soft for a metal. It is harder than lead and must be extracted by electrolysis from a fused salt like calcium chloride.

1808 by Sir Humphrey Davy, England.

DISCOVERY

Latin, calx ('lime', 'limestone').

ETYMOLOGY

Calcium

Element

Ca

Symbol

20

20 Atomic Number

Atomic Number

Alkaline Earth

Classification

7440-70-2

CAS Number

Silver

Elemental Colour

-

Refractive Index

0.310

0.310 Poisson Ratio

Poisson Ratio

25.857 cm³

Molar Volume

167.00M Pa, 1.648'2k Atm

Brinell Hardness

1.75

1.75 Mohs Hardness

Mohs Hardness

-

Vickers Hardness

3,810 m/s, Mach 11.107'9

3,810 m/s

Speed of Sound

17.00G Pa, 167.777'0k Atm

167.777'0k Atm

Bulk Modulus

7.40G Pa, 73.032'3k Atm

73.032'3k Atm

Shear Modulus

20.00G Pa, 197.384'7k Atm

197.384'7k Atm

Young Modulus

Allotropes

1,115.15 K, 842.00 °C

842.00 °C

Melting Point

1,757.15 K, 1,484.00 °C

1,484.00 °C

Boiling Point

-

Automatic Ignition

-

Flashpoint

-

Critical Temperature

-

Critical Pressure

200.000'000 W/(m K)

Thermal Conductivity

0.000'022'3 K^-1

Thermal Expansion

631.00 J/(kg K)

Specific Heat

8.540 kJ/mol

Heat Fusion

155.000 kJ/mol

Heat Vaporisation

990.000 J/(kg K)

Heat Combustion

-

Curie Point

-

Neel Point

-

Adiabatic Index

Solid

Phase

Conductor

Electrical Type

29.00M S/m

Conductivity

34.00n Ω.m

Resistivity

-

Superconducting Point

Paramagnetic

Magnetic Type

0.000'000'013'8

Mass Susceptibility

0.000'000'000'553'10

Molar Susceptibility

0.000'021'390'00

Volume Susceptibility

Material Composition

0.003 %

Universe

1.1 %

Meteorites

0.008 %

Sun

5 %

Earth Crust

0.000'62 %

Oceans

1.4 %

Humans

40.078'022'7

Atomic Weight

194 pm

Atomic Radius

171 pm

Covalent Radius Single Bond

147 pm

Covalent Radius Double Bond

133 pm

Covalent Radius Triple Bond

231 pm

Van der Waals Radius

[Ar]4s²

Electron Configuration

Cubic, Face-centred

Crystal Structure

1.550'00 g/cm³

Density as Solid

1.378'00 g/cm³

Density as Liquid

-

Density as Gas

Fm_3m

Space Group Name

225

225 Space Group Number

Space Group Number

π/2, π/2 & π/2

Lattice Angles

558.84, 558.84 & 558.84 pm

Lattice Constants

2

2 Valence

Valence

1

1 Electronegativity

Electronegativity

2.37 kJ/mol

Electron Affinity

Ionisation Energy

Stable

Half Life

Stable

Lifetime

4s² = 4, 0, 0, -1/2

Quantum Numbers

2.830'00 b σ_s

Neutron Cross Section

0.430'00 b σ_a

Neutron Mass Absorption

Stable Isotopes

Unstable Isotopes

Isotopes Overview

Isotope	Stability	Symbol	Type	Protons		Neutrons		Spin	Parity	Mass		Abundance		Mass Measure	Mass Excess		Binding Energy		Dipole Moment		Quadrupole Moment		Halflife in Years		Halflife in Seconds		A01 Decay Probability		A01 Decay Mode	A01 Decay Energy		A01 Decay Daughter	A01 Decay Link	A02 Decay Probability		A02 Decay Mode	A02 Decay Energy		A02 Decay Daughter	A02 Decay Link	Y01 Decay Product Yield		Y01 Decay Product Nuclide	Y02 Decay Product Yield		Y02 Decay Product Nuclide	Y03 Decay Product Yield		Y03 Decay Product Nuclide
Isotope_020_ca_34_u	Unstable	³⁴Ca	Boson	20	p	14	n	0	1	34.014'120'000'0	u	~ 0	%	~ 0	13.153'000'000'0	MeV	7.224'000'000'0	MeV	-		-		1.11E-15	year	35.000	nano-seconds ( x⁻⁹ )	?	%	2p	775.000	keV	³²Ar	³⁴Ca > [ ? % , 2p , 775.0 keV ] > ³²Ar								?	%	³²S	?	%	²⁸Si	?	%	³¹P
Isotope_020_ca_35_u	Unstable	³⁵Ca	Fermion	20	p	15	n	1/2	1	35.004'940'000'0	u	~ 0	%	~ 0	4.602'000'000'0	MeV	7.493'000'000'0	MeV	-		-		8.14E-10	year	25.700	milli-seconds ( x⁻³ )	95.700'000	%	β+p	?	keV	³⁴Ar	³⁵Ca > [ 95.7 % , β+p , ? keV ] > ³⁴Ar	4.200'000	%	β+2p	?	keV	³³Cl	³⁵Ca > [ 4.2 % , β+2p , ? keV ] > ³³Cl	95.700'000	%	³⁴S	4.200'000	%	³³S
Isotope_020_ca_36_u	Unstable	³⁶Ca	Boson	20	p	16	n	0	1	35.993'087'063'0	u	~ 0	%	~ 0	-6.439'359'000'0	MeV	7.815'551'000'0	MeV	-		-		3.23E-9	year	102.000	milli-seconds ( x⁻³ )	56.800'000	%	β+p	?	keV	³⁵Ar	³⁶Ca > [ 56.8 % , β+p , ? keV ] > ³⁵Ar	43.000'000	%	β+	9,964.600	keV	³⁶K	³⁶Ca > [ 43 % , β+ , 9,964.6 keV ] > ³⁶K	56.820'640	%	³⁵Cl	0.001'462	%	³²S	?	%	³⁶S
Isotope_020_ca_37_u	Unstable	³⁷Ca	Fermion	20	p	17	n	3/2	1	36.985'870'269'0	u	~ 0	%	~ 0	-13.161'760'000'0	MeV	8.004'150'000'0	MeV	-		-		5.74E-9	year	181.100	milli-seconds ( x⁻³ )	82.100'000	%	β+p	?	keV	³⁶Ar	³⁷Ca > [ 82.1 % , β+p , ? keV ] > ³⁶Ar								?	%	³⁶S
Isotope_020_ca_38_u	Unstable	³⁸Ca	Boson	20	p	18	n	0	1	37.976'318'452'0	u	~ 0	%	~ 0	-22.059'220'000'0	MeV	8.240'062'000'0	MeV	-		-		1.39E-8	year	440.000	milli-seconds ( x⁻³ )	100.000'000	%	β+	5,719.270	keV	³⁸K	³⁸Ca > [ 100 % , β+ , 5,719.27 keV ] > ³⁸K								100.000'000	%	³⁸Ar
Isotope_020_ca_39_u	Unstable	³⁹Ca	Fermion	20	p	19	n	3/2	1	38.970'719'725'0	u	~ 0	%	~ 0	-27.274'400'000'0	MeV	8.369'457'000'0	MeV	1.021'680'000'0	nm	-		2.72E-8	year	859.600	milli-seconds ( x⁻³ )	100.000'000	%	β+	5,510.410	keV	³⁹K	³⁹Ca > [ 100 % , β+ , 5,510.41 keV ] > ³⁹K								100.000'000	%	³⁹K
Isotope_020_ca_40_s	Stable	⁴⁰Ca	Boson	20	p	20	n	0	1	39.962'590'983'0	u	96.941'000	%	38.740'135'324'8	-34.846'275'000'0	MeV	8.551'301'000'0	MeV	-		-		-				?	%	2β+	-1,850.780	keV	⁴⁰Ar	⁴⁰Ca > [ ? % , 2β+ , -1,850.78 keV ] > ⁴⁰Ar								?	%	⁴⁰Ar
Isotope_020_ca_41_u	Unstable	⁴¹Ca	Fermion	20	p	21	n	7/2	-1	40.962'278'062'0	u	~ 0	%	~ 0	-35.137'759'000'0	MeV	8.546'703'000'0	MeV	-1.594'781'000'0	nm	-0.080'000'000'0	b	1.02E+5	years	3.222	tera-seconds ( x¹² )	100.000'000	%	ϵ	421.315	keV	⁴¹K	⁴¹Ca > [ 100 % , ϵ , 421.315 keV ] > ⁴¹K								100.000'000	%	⁴¹K
Isotope_020_ca_42_s	Stable	⁴²Ca	Boson	20	p	22	n	0	1	41.958'618'014'0	u	0.647'000	%	0.271'472'258'6	-38.547'072'000'0	MeV	8.616'559'000'0	MeV	-		-		-
Isotope_020_ca_43_s	Stable	⁴³Ca	Fermion	20	p	23	n	7/2	-1	42.958'766'628'0	u	0.135'000	%	0.057'994'334'9	-38.408'639'000'0	MeV	8.600'659'000'0	MeV	-1.317'643'000'0	nm	-0.049'000'000'0	b	-
Isotope_020_ca_44_s	Stable	⁴⁴Ca	Boson	20	p	24	n	0	1	43.955'481'754'0	u	2.086'000	%	0.916'911'349'4	-41.468'479'000'0	MeV	8.658'170'000'0	MeV	-		-		-
Isotope_020_ca_45_u	Unstable	⁴⁵Ca	Fermion	20	p	25	n	7/2	-1	44.956'186'566'0	u	~ 0	%	~ 0	-40.811'950'000'0	MeV	8.630'540'000'0	MeV	-1.327'400'000'0	nm	0.046'000'000'0	b	4.45E-1	year	14.055	mega-seconds ( x⁶ )	100.000'000	%	β-	255.842	keV	⁴⁵Sc	⁴⁵Ca > [ 100 % , β- , 255.842 keV ] > ⁴⁵Sc								100.000'000	%	⁴⁵Sc
Isotope_020_ca_46_s	Stable	⁴⁶Ca	Boson	20	p	26	n	0	1	45.953'692'587'0	u	0.004'000	%	0.001'838'147'7	-43.135'077'000'0	MeV	8.668'885'000'0	MeV	-		-		-				?	%	2β-	688.350	keV	⁴⁶Ti	⁴⁶Ca > [ ? % , 2β- , 688.35 keV ] > ⁴⁶Ti								?	%	⁴⁶Ti
Isotope_020_ca_47_u	Unstable	⁴⁷Ca	Fermion	20	p	27	n	7/2	-1	46.954'546'006'0	u	~ 0	%	~ 0	-42.340'123'000'0	MeV	8.639'257'000'0	MeV	-1.380'000'000'0	nm	0.021'000'000'0	b	1.19E-2	year	376.350	kilo-seconds ( x³ )	100.000'000	%	β-	1,992.000	keV	⁴⁷Sc	⁴⁷Ca > [ 100 % , β- , 1,992.0 keV ] > ⁴⁷Sc								100.000'000	%	⁴⁷Ti
Isotope_020_ca_48_u	Unstable	⁴⁸Ca	Boson	20	p	28	n	0	1	47.952'534'177'0	u	0.187'000	%	0.089'671'238'9	-44.214'129'000'0	MeV	8.666'467'000'0	MeV	-		-		5.39E+19	years	1,700.955	yotta-seconds ( x²⁴ )	?	%	2β-	4,273.600	keV	⁴⁸Ti	⁴⁸Ca > [ ? % , 2β- , 4,273.6 keV ] > ⁴⁸Ti	?	%	β-	281.970	keV	⁴⁸Sc	⁴⁸Ca > [ ? % , β- , 281.97 keV ] > ⁴⁸Sc	?	%	⁴⁸Ti
Isotope_020_ca_49_u	Unstable	⁴⁹Ca	Fermion	20	p	29	n	3/2	-1	48.955'674'148'0	u	~ 0	%	~ 0	-41.289'265'000'0	MeV	8.594'630'000'0	MeV	-		-		1.66E-5	year	523.098	seconds ( x⁰ )	100.000'000	%	β-	5,263.100	keV	⁴⁹Sc	⁴⁹Ca > [ 100 % , β- , 5,263.1 keV ] > ⁴⁹Sc								100.000'000	%	⁴⁹Ti
Isotope_020_ca_50_u	Unstable	⁵⁰Ca	Boson	20	p	30	n	0	1	49.957'518'962'0	u	~ 0	%	~ 0	-39.570'832'000'0	MeV	8.549'795'000'0	MeV	-		-		4.40E-7	year	13.900	seconds ( x⁰ )	100.000'000	%	β-	4,966.100	keV	⁵⁰Sc	⁵⁰Ca > [ 100 % , β- , 4,966.1 keV ] > ⁵⁰Sc								100.000'000	%	⁵⁰Ti
Isotope_020_ca_51_u	Unstable	⁵¹Ca	Fermion	20	p	31	n	3/2	-1	50.961'499'214'0	u	~ 0	%	~ 0	-35.863'251'000'0	MeV	8.467'716'000'0	MeV	-		-		3.17E-7	year	10.000	seconds ( x⁰ )	100.000'000	%	β-	7,354.900	keV	⁵¹Sc	⁵¹Ca > [ 100 % , β- , 7,354.9 keV ] > ⁵¹Sc	?	%	β-n	602.300	keV	⁵⁰Sc	⁵¹Ca > [ ? % , β-n , 602.3 keV ] > ⁵⁰Sc	100.000'000	%	51v	?	%	⁵⁰Ti
Isotope_020_ca_52_u	Unstable	⁵²Ca	Boson	20	p	32	n	0	1	51.965'100'000'0	u	~ 0	%	~ 0	-32.509'141'000'0	MeV	8.395'590'000'0	MeV	-		-		1.46E-7	year	4.600	seconds ( x⁰ )	98.000'000	%	β-	7,847.000	keV	⁵²Sc	⁵²Ca > [ 98 % , β- , 7,847.0 keV ] > ⁵²Sc	2.000'000	%	β-n	2,638.000	keV	⁵¹Sc	⁵²Ca > [ 2 % , β-n , 2,638.0 keV ] > ⁵¹Sc	98.000'000	%	⁵²Cr	2.000'000	%	⁵¹V
Isotope_020_ca_53_u	Unstable	⁵³Ca	Fermion	20	p	33	n	3/2	-1	52.970'050'000'0	u	~ 0	%	~ 0	-27.898'000'000'0	MeV	8.302'000'000'0	MeV	-		-		2.85E-9	year	90.000	milli-seconds ( x⁻³ )	70.000'000	%	β-	9,725.000	keV	⁵³Sc	⁵³Ca > [ 70 % , β- , 9,725.0 keV ] > ⁵³Sc	30.000'000	%	β-n	4,387.000	keV	⁵²Sc	⁵³Ca > [ 30 % , β-n , 4,387.0 keV ] > ⁵²Sc	70.000'000	%	⁵³Cr	30.000'000	%	⁵²Cr
Isotope_020_ca_54_u	Unstable	⁵⁴Ca	Boson	20	p	34	n	0	1	53.974'350'000'0	u	~ 0	%	~ 0	-23.893'000'000'0	MeV	8.224'000'000'0	MeV	-		-		1.58E-9	year	50.000	milli-seconds ( x⁻³ )	?	%	β-	10,326.000	keV	⁵⁴Sc	⁵⁴Ca > [ ? % , β- , 10,326.0 keV ] > ⁵⁴Sc	?	%	β-n	5,659.000	keV	⁵³Sc	⁵⁴Ca > [ ? % , β-n , 5,659.0 keV ] > ⁵³Sc	?	%	⁵⁴Cr	?	%	⁵³Cr	?	%	⁵²Cr
Isotope_020_ca_55_u	Unstable	⁵⁵Ca	Boson	20	p	35	n	5/2	-1	54.980'550'000'0	u	~ 0	%	~ 0	-18.118'000'000'0	MeV	8.116'000'000'0	MeV	-		-		9.51E-10	year	30.000	milli-seconds ( x⁻³ )	?	%	β-	11,460.000	keV	⁵⁵Sc	⁵⁵Ca > [ ? % , β- , 11,460.0 keV ] > ⁵⁵Sc								?	%	⁵⁵Mn	?	%	⁵⁴Cr
Isotope_020_ca_56_u	Unstable	⁵⁶Ca	Boson	20	p	36	n	0	1	55.985'570'000'0	u	~ 0	%	~ 0	-13.441'000'000'0	MeV	8.032'000'000'0	MeV	-		-		3.17E-10	year	10.000	milli-seconds ( x⁻³ )	?	%	β-	11,830.000	keV	⁵⁶Sc	⁵⁶Ca > [ ? % , β- , 11,830.0 keV ] > ⁵⁶Sc								?	%	⁵⁵Mn	?	%	⁵⁶Fe
Isotope_020_ca_57_u	Unstable	⁵⁷Ca	Fermion	20	p	37	n	5/2	1	56.992'356'000'0	u	~ 0	%	~ 0	-7.120'000'000'0	MeV	7.922'000'000'0	MeV	-		-		1.58E-10	year	5.000	milli-seconds ( x⁻³ )	?	%	β-	13,570.000	keV	⁵⁷Sc	⁵⁷Ca > [ ? % , β- , 13,570.0 keV ] > ⁵⁷Sc	?	%	β-n	10,080.000	keV	⁵⁶Sc	⁵⁷Ca > [ ? % , β-n , 10,080.0 keV ] > ⁵⁶Sc	?	%	⁵⁵Mn	?	%	⁵⁷Fe	?	%	⁵⁶Fe

20 – Calcium, Ca

20 – Calcium, Ca

20 – Calcium, Ca

20 – Calcium, Ca

20 – Calcium, Ca

Spectrograph

Elemental Tile

Calcium

Spectrograph

Elemental Tile

Calcium

Spectrograph

Elemental Tile

Calcium

Spectrograph

Elemental Tile

Calcium

Spectrograph

Elemental Tile

Calcium