Kalsium

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20 kaliumKalsiumskandium
Mg

Ca

Sr
Ca-TableImage.png
Umum
Ngaran, Lambang, Nomer Kalsium, Ca, 20
Dérét kimia logam alkali taneuh
Golongan, Periode, Blok 2, 4, s
Warna bodas semu pérak
Ca,20.jpg
Beurat atom baku 40.078(4)  g·mol−1
Konfigurasi éléktron [Ar] 4s2
Éléktron per cangkang 2, 8, 8, 2
Pasipatan fisik
Fase padet
Dénsitas (dina h.r.) 1.55 g/cm³
Dénsitas cairan dina t.l. 1.378 g/cm³
Titik lééh 1115 K
(842 °C, 1548 °F)
Titik golak 1757 K
(1484 °C, 2703 °F)
Panas fusi 8.54  kJ·mol−1
Panas panguapan 154.7  kJ·mol−1
Kapasitas panas (25 °C) 25.929  J·mol−1·K−1
Tekanan uap
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 864 956 1071 1227 1443 1755
Pasipatan atom
Struktur kristal kubus museur beungeut
Wilangan oksidasi 2
(oksida basa kuat)
Éléktronégativitas 1.00 (skala Pauling)
Énergi ionisasi
(lianna)
1st: 589.8 kJ/mol
2nd: 1145.4 kJ/mol
3rd: 4912.4 kJ/mol
Radius atom 180pm
Radius atom (itung.) 194  pm
Radius kovalén 174  pm
Unak-anik
Susunan magnétik paramagnétik
Résistivitas listrik (20 °C) 33.6 nΩ·m
Konduktivitas panas (300 K) 201  W·m−1·K−1
Ékspansi panas (25 °C) 22.3 µm/(m·K)
Laju sora (pelat ipis) (20 °C) 3810 m/s
Modulus Young 20 GPa
Modulus Shear 7.4 GPa
Modulus Bulk 17 GPa
Nisbah Poisson 0.31
Kateuasan Mohs 1.75
Kateuasan Brinell 167 MPa
Nomer régister CAS 7440-70-2
Isotop penting
Artikel utama: Isotop kalsium
iso KA umur-nyatengah UR ÉU (MeV) HU
40Ca 96.941% Ca stabil ngandung 20 neutron
41Ca syn 1.03×105 y ε - 41K
42Ca 0.647% Ca stabil ngandung 22 neutron
43Ca 0.135% Ca stabil ngandung 23 neutron
44Ca 2.086% Ca stabil ngandung 24 neutron
45Ca syn 162.7 d β- 0.258 45Sc
46Ca 0.004% >2.8×1015 y β-β-  ? 46Ti
47Ca syn 4.536 d β- 0.694, 1.99 47Sc
γ 1.297 -
48Ca 0.187% >4×1019 y β-β-  ? 48Ti
Rujukan

Kalsium ngarupakeun unsur kimiawi na tabel periodik nu lambangna Ca sarta wilangan atom 20. Kalsium is a soft grey alkaline earth metal nu dipaké salaku agén pangréduksi na ékstraksi thorium, zirconium, jeung uranium. Unsur ieu ogé mangrupa unsur kalima nu paling ngaleuyah na kulit Marcapada. Penting pikeun organisme hirup, utamana dina fisiologi sél.

Ciri penting[édit | sunting sumber]

Kalsium téh unsur teuas nu dimurnikeun ku jalan éléktrolisis kalsium fluorida, nu mun kaduruk seuneuna konéng-héjo, sarta ngabentuk nitrida bodas mun keuna ku udara. Dina cai, kalsium bakal jadi kalsium hidroksida.

Larapan[édit | sunting sumber]

Kalsium téh salah sahiji komponén penting katuangan, kurang asupanana bisa ngabalukarkeun gangguan formasi tulang jeung huntu. Tapi konsumsi kalsium gé ulah nepi ka loba teuing, sabab bisa ngabalukarkeun batu ginjal. Kalsium bisa diserep ku peujit mun aya Vitamin D.

Pikeun leuwih lengkep ngeunaan Ca dina kahirupan, mangga aos kalsium dina biologi.

History[édit | sunting sumber]

(Latin calx, lime) Lime was prepared and used by the Romans as early as the 1st century, but calcium was not discovered until 1808. After learning that Berzelius and Pontin prepared calcium amalgam by electrolyzing lime in mercury, Sir Humphry Davy was able to isolate the impure metal.

Occurrence[édit | sunting sumber]

Calcium is the fifth most abundant element in the earth's crust (forming more than 3%) and is an essential part of leaves, bones, teeth, and shells. Due to its chemical reactivity with air and water, calcium is never found in nature unbound to other elements, except in living organisms where Ca2+ plays a key role in cell physiology. This metallic element is found in quantity in limestone, gypsum, and fluorite. Apatite is the fluorophosphate or chlorophosphate of calcium. Electrolysis of molten calcium chloride (CaCl2) can be used to isolate pure calcium.
Isolation (* follow):
cathode: Ca2+* + 2e- --> Ca
anode: Cl-* --> ½Cl2 (gas) + e-

Compounds[édit | sunting sumber]

Quicklime (CaO) is used in many chemical refinery processes and is made by heating and carefully adding water to limestone. When CaO is mixed with sand it hardens into a mortar and is turned into plaster by carbon dioxide uptake. Mixed with other compounds, CaO forms an important part of Portland cement.

When water percolates through limestone or other soluble carbonate rocks, it partially disolves part of the rock and causes cave formation and characteristic stalactites and stalagmites and also forms hard water. Other important calcium compounds are nitrate, sulfide, chloride, carbide, cyanamide, and hypochlorite.

Isotop[édit | sunting sumber]

Kalsium boga genep isotop stabil, dua di antarana aya di alam: Ca-40 stabil jeung Ca-41 radioaktif nu umur-satengahna = 103.000 taun. 97% unsur ieu aya dina wujud Ca-40. Ca-40 téh turunan tina luruhna K-40, nu ogé ngahasilkeun Ar-40.

Baca ogé: gangguan métabolisme kalsium

Tumbu kaluar[édit | sunting sumber]