Calcium

  • calcium, 20ca
    calcium unter argon schutzgasatmosphäre.jpg
    calcium
    appearancedull gray, silver; with a pale yellow tint[1]
    standard atomic weight ar, std(ca)40.078(4)[2]
    calcium in the periodic table
    hydrogen helium
    lithium beryllium boron carbon nitrogen oxygen fluorine neon
    sodium magnesium aluminium silicon phosphorus sulfur chlorine argon
    potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton
    rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon
    caesium barium lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury (element) thallium lead bismuth polonium astatine radon
    francium radium actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson
    mg

    ca

    sr
    potassiumcalciumscandium
    atomic number (z)20
    groupgroup 2 (alkaline earth metals)
    periodperiod 4
    blocks-block
    element category  alkaline earth metal
    electron configuration[ar] 4s2
    electrons per shell2, 8, 8, 2
    physical properties
    phase at stpsolid
    melting point1115 k ​(842 °c, ​1548 °f)
    boiling point1757 k ​(1484 °c, ​2703 °f)
    density (near r.t.)1.55 g/cm3
    when liquid (at m.p.)1.378 g/cm3
    heat of fusion8.54 kj/mol
    heat of vaporisation154.7 kj/mol
    molar heat capacity25.929 j/(mol·k)
    vapour pressure
    p (pa) 1 10 100 1 k 10 k 100 k
    at t (k) 864 956 1071 1227 1443 1755
    atomic properties
    oxidation states+1,[3] +2 (a strongly basic oxide)
    electronegativitypauling scale: 1.00
    ionisation energies
    • 1st: 589.8 kj/mol
    • 2nd: 1145.4 kj/mol
    • 3rd: 4912.4 kj/mol
    • (more)
    atomic radiusempirical: 197 pm
    covalent radius176±10 pm
    van der waals radius231 pm
    color lines in a spectral range
    spectral lines of calcium
    other properties
    natural occurrenceprimordial
    crystal structureface-centred cubic (fcc)
    face-centered cubic crystal structure for calcium
    speed of sound thin rod3810 m/s (at 20 °c)
    thermal expansion22.3 µm/(m·k) (at 25 °c)
    thermal conductivity201 w/(m·k)
    electrical resistivity33.6 nΩ·m (at 20 °c)
    magnetic orderingdiamagnetic
    magnetic susceptibility+40.0·10−6 cm3/mol[4]
    young's modulus20 gpa
    shear modulus7.4 gpa
    bulk modulus17 gpa
    poisson ratio0.31
    mohs hardness1.75
    brinell hardness170–416 mpa
    cas number7440-70-2
    history
    discovery and first isolationhumphry davy (1808)
    main isotopes of calcium
    iso­tope abun­dance half-life (t1/2) decay mode pro­duct
    40ca 96.941% stable
    41ca trace 9.94×104 y ε 41k
    42ca 0.647% stable
    43ca 0.135% stable
    44ca 2.086% stable
    45ca syn 162.6 d β 45sc
    46ca 0.004% stable
    47ca syn 4.5 d β 47sc
    γ
    48ca 0.187% 6.4×1019 y ββ 48ti
    category category: calcium
    | references

    calcium is a chemical element with the symbol ca and atomic number 20. as an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. its physical and chemical properties are most similar to its heavier homologues strontium and barium. it is the fifth most abundant element in earth's crust and the third most abundant metal, after iron and aluminium. the most common calcium compound on earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. the name derives from latin calx "lime", which was obtained from heating limestone.

    some calcium compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. pure calcium was isolated in 1808 via electrolysis of its oxide by humphry davy, who named the element. calcium compounds are widely used in many industries: in foods and pharmaceuticals for calcium supplementation, in the paper industry as bleaches, as components in cement and electrical insulators, and in the manufacture of soaps. on the other hand, the metal in pure form has few applications due to its high reactivity; still, in small quantities it is often used as an alloying component in steelmaking, and sometimes, as a calcium–lead alloy, in making automotive batteries.

    calcium is the most abundant metal and the fifth-most abundant element in the human body.[5] as electrolytes, calcium ions play a vital role in the physiological and biochemical processes of organisms and cells: in signal transduction pathways where they act as a second messenger; in neurotransmitter release from neurons; in contraction of all muscle cell types; as cofactors in many enzymes; and in fertilization.[5] calcium ions outside cells are important for maintaining the potential difference across excitable cell membranes, protein synthesis, and bone formation.[5][6]

  • characteristics
  • history
  • occurrence and production
  • uses
  • food sources
  • biological and pathological role
  • safety
  • see also
  • references
  • bibliography

Calcium, 20Ca
Calcium unter Argon Schutzgasatmosphäre.jpg
Calcium
Appearancedull gray, silver; with a pale yellow tint[1]
Standard atomic weight Ar, std(Ca)40.078(4)[2]
Calcium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Mg

Ca

Sr
potassiumcalciumscandium
Atomic number (Z)20
Groupgroup 2 (alkaline earth metals)
Periodperiod 4
Blocks-block
Element category  Alkaline earth metal
Electron configuration[Ar] 4s2
Electrons per shell2, 8, 8, 2
Physical properties
Phase at STPsolid
Melting point1115 K ​(842 °C, ​1548 °F)
Boiling point1757 K ​(1484 °C, ​2703 °F)
Density (near r.t.)1.55 g/cm3
when liquid (at m.p.)1.378 g/cm3
Heat of fusion8.54 kJ/mol
Heat of vaporisation154.7 kJ/mol
Molar heat capacity25.929 J/(mol·K)
Vapour pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 864 956 1071 1227 1443 1755
Atomic properties
Oxidation states+1,[3] +2 (a strongly basic oxide)
ElectronegativityPauling scale: 1.00
Ionisation energies
  • 1st: 589.8 kJ/mol
  • 2nd: 1145.4 kJ/mol
  • 3rd: 4912.4 kJ/mol
  • (more)
Atomic radiusempirical: 197 pm
Covalent radius176±10 pm
Van der Waals radius231 pm
Color lines in a spectral range
Spectral lines of calcium
Other properties
Natural occurrenceprimordial
Crystal structureface-centred cubic (fcc)
Face-centered cubic crystal structure for calcium
Speed of sound thin rod3810 m/s (at 20 °C)
Thermal expansion22.3 µm/(m·K) (at 25 °C)
Thermal conductivity201 W/(m·K)
Electrical resistivity33.6 nΩ·m (at 20 °C)
Magnetic orderingdiamagnetic
Magnetic susceptibility+40.0·10−6 cm3/mol[4]
Young's modulus20 GPa
Shear modulus7.4 GPa
Bulk modulus17 GPa
Poisson ratio0.31
Mohs hardness1.75
Brinell hardness170–416 MPa
CAS Number7440-70-2
History
Discovery and first isolationHumphry Davy (1808)
Main isotopes of calcium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
40Ca 96.941% stable
41Ca trace 9.94×104 y ε 41K
42Ca 0.647% stable
43Ca 0.135% stable
44Ca 2.086% stable
45Ca syn 162.6 d β 45Sc
46Ca 0.004% stable
47Ca syn 4.5 d β 47Sc
γ
48Ca 0.187% 6.4×1019 y ββ 48Ti
Category Category: Calcium
| references

Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The name derives from Latin calx "lime", which was obtained from heating limestone.

Some calcium compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. Pure calcium was isolated in 1808 via electrolysis of its oxide by Humphry Davy, who named the element. Calcium compounds are widely used in many industries: in foods and pharmaceuticals for calcium supplementation, in the paper industry as bleaches, as components in cement and electrical insulators, and in the manufacture of soaps. On the other hand, the metal in pure form has few applications due to its high reactivity; still, in small quantities it is often used as an alloying component in steelmaking, and sometimes, as a calcium–lead alloy, in making automotive batteries.

Calcium is the most abundant metal and the fifth-most abundant element in the human body.[5] As electrolytes, calcium ions play a vital role in the physiological and biochemical processes of organisms and cells: in signal transduction pathways where they act as a second messenger; in neurotransmitter release from neurons; in contraction of all muscle cell types; as cofactors in many enzymes; and in fertilization.[5] Calcium ions outside cells are important for maintaining the potential difference across excitable cell membranes, protein synthesis, and bone formation.[5][6]