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Line 1: + − + − + + + + + + + + + + + − == Physical properties ==+ − − == Chemical properties == − − It reacts with water to produce [[hydrogen]] and [[calcium hydroxide]]. It reacts with water very fast when it is powdered. When it is in a chunk, it starts reacting slowly because calcium hydroxide makes a coating that does not dissolve on the calcium. If a little [[acid]] is added to calcium hydroxide, it dissolves it, making the calcium react very fast. It burns when powdered to make a reddish flame. This makes [[calcium oxide]]. It also makes [[calcium nitride]] when heated. It can react with [[halogen]]s to make calcium halides like [[calcium chloride]] with [[chlorine]]. − + − + − + − + − + − + − + − + − + + + + + − + Line 32:
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Line 55: − + − + + + + + + + + + − == In the ground ==+ − + − + − + − It is important to know how cells work. Many cells have ''calcium channels'' on their surface. These are openings where calcium ions can enter the cell. The cell is told to act and it opens the channels. Once in the cell calcium ions activates many [[protein]]s to do specific things. For example, when it goes into [[muscle]] cells, it makes them ''contract'' (shorten so the muscle pulls.) When it goes into [[nerve]] cells, it triggers electrical impulses that send a message. When it goes into [[white blood cell]]s, it makes them fight germs.+ + − + − Sometimes cells are unhealthy and need to die in for the body to replace them with new, healthy cells. This keeps the whole [[organism]] healthy. Cells know when they should die and can trigger reactions to end their life cycles in many ways. When this happens it is called [[apoptosis]], also known as a 'programmed cell death' (''planned'' cell death.) One way cells accomplish ''apoptosis'' by taking in toxic levels of calcium ions.+ + + − + − − − + − − Organisms need to keep calcium ion levels very well controlled. High calcium levels are bad, and low calcium levels are bad. − The body controls this by changing+ − * how much calcium we get from the food we eat+ − * how much calcium we lose in [[urine]]+ − * how much calcium is put in bones+ − The control of calcium in the body is called ''calcium [[metabolism]]''. Too little calcium can cause [[osteoporosis]]. − The body controls calcium levels with many [[hormone]]s. Calcitonin, Parathyroid hormone ([[acronym]] PTH), and [[Vitamin D]] are the most important hormones in ''calcium metabolism''. (Vitamin D works as a hormone but it is called a [[vitamin]].)+ − + − − − − Calcium is used in the [[reduction (chemistry)|reduction]] of other metals. It can also be used to make alloys with other metals. − − [[File:Concrete pouring 0020.jpg|thumb|right|Concrete used to make a building]] − Calcium compounds are also important in [[chemistry]]. It is important for making things. It is a part of [[cement]] which is needed to make [[concrete]] (a hard substance that many buildings are made from.) − Calcium is part of [[calcium oxide]]. Calcium oxide is used to make [[paper]], [[pottery]], food, and to purify water (make it good to drink.) Calcium carbonate is used as a calcium supplement. Calcium permanganate can be used as a rocket [[propellant|propellant]].+ − + Line 102:
Line 112: − + + + − == Other websites ==+ − * [http://en.citizendium.org/wiki/Calcium Calcium] -Citizendium
KS update 1.4
{{Merge from|Calcium (diet)|date=April 2026}}
{{infobox calcium}}
{{infobox calcium}}
[[File:Calcium unter Argon Schutzgasatmosphäre.jpg|thumb|Very pure calcium metal, not corroded]]
[[File:Calcium unter Argon Schutzgasatmosphäre.jpg|thumb|Very pure calcium metal, not corroded]]
[[File:Calcium.jpg|thumb|Calcium metal in air, corroded]]
[[File:Calcium.jpg|thumb|Calcium metal in air, corroded]]
'''Calcium''' is a [[chemical element]]. Its symbol on the [[periodic table]] (a list of all the elements) is '''Ca'''. Its [[atomic number]] is 20. (The atomic number says where Calcium sits in the periodic table.) It has 20 [[proton]]s and 20 [[electron]]s (if is an atom, see [[ion]]). The most common [[isotope]]s are Ca-40 and Ca-44. Its [[mass number]] is about 40.08.
'''Calcium''' is a [[chemical element]]. Its symbol on the [[periodic table]] (a list of all the elements) is '''Ca'''. and its [[atomic number]] is 20.<ref name=":1">{{Cite web|title=Atomic Weight of Calcium {{!}} Commission on Isotopic Abundances and Atomic Weights|url=https://www.ciaaw.org/calcium.htm|access-date=2026-04-09|website=www.ciaaw.org}}</ref> The atomic number says where Calcium sits in the periodic table. It has 20 [[proton]]s and 20 [[electron]]s (if is an atom, see [[ion]]). The most common [[isotope]]s are Ca-40 and Ca-44. Its [[mass number]] is about 40.07.<ref name=":1" />
Calcium is very important in the human body, for making [[bone]]s and for other purposes.
Calcium is not found as a metal in the ground (a [[native element mineral]]) because it is too [[chemical reactivity|reactive]].<ref>{{cite web|title=Calcium: the essentials|url=http://www.webelements.com/calcium/|publisher=WebElements|accessdate=7 February 2016}}</ref> [[Calcium carbonate]], also known as [[calcite]], is the most common calcium mineral.
Calcium is very important in the human body, for making [[bone]]s and is an inorganic component found in bones, alongside phosphate.<ref name=":4">{{Cite book|title=MCAT Complete 7-book subject review 2025 -2026, set includes books, online prep, 3 ... practise tests|date=2024|publisher=KAPLAN North America, LLC dba kaplan Publishing|isbn=978-1-5062-9438-4|editor-last=Macnow|editor-first=Alexander Stone|location=Fort Lauderdale, Florida|editor-last2=Kaplan Publishing}}</ref> 99% of calcium in the bone is stored in bones.<ref name=":4" /> It is used in nerve and muscle (including the heart muscle) contraction. The name comes "calx", the [[Latin]] name for lime, or limestone.<ref name=":1" />[[File:Calcite-cu01abg.jpg|thumb|Calcite]]
== Properties ==
== Properties ==
Calcium is a soft white-gray [[opaque]] [[metal]]. It is [[solid]] at [[room temperature]]. The [[crystal structure]] of calcium [[metal]] changes between two [[allotrope]]s, being [[face-centred cubic]] at room temperature and [[body-centred cubic]] above {{convert|464|C|F K}}.<ref>{{cite journal|doi=10.1149/1.2430364}}</ref> It [[melt]]s at {{convert|842|C|F K}}.
It does not conduct electricity as well as [[copper]], but is much lighter in weight.{{cn}}
== Chemistry ==
[[File:Calcium air 2.theora.webm|thumb|Calcium metal burning]]
Calcium is the third [[alkaline earth metal]], and has similar chemistry to the rest of the [[group (periodic table)|group]]. It is a strong [[reducing agent]] and [[base (chemistry)|base]] with two [[valence electron]]s.
Calcium metal reacts with [[oxygen]] in the [[air]] to make a layer of [[calcium oxide]] on the outside of the metal. This stops further chemical reactions ([[passivation]]) until the layer is removed. This compound is a strong [[Brønsted base]] and reacts with [[Brønsted acid]]s to make calcium [[salt (chemistry)|salt]]s of the [[conjugate base]].{{cn}} Non-passivated calcium metal can also make salts by [[redox|reducing]] Brønsted acids directly to [[hydrogen]] [[gas]].{{cn}} If the calcium salt of an acid is [[soluble]] in that acid or the [[solvent]] being used, the calcium-acid reaction is very fast and gives off a lot of [[heat]].
Calcium is a soft white-gray [[metal]]. It is a solid and is opaque. It is an [[alkaline earth metal]]. Its [[melting point]] is hotter than most other reactive metals. It is a little harder than [[lead]]. It has two [[allotrope]]s. It does not conduct electricity as well as copper, but is much lighter in weight.
[[File:Calcium air 2.theora.ogv|thumb|Calcium metal burning]]
== Calcium compounds ==
== Calcium compounds ==
Calcium forms chemical compounds in the +2 [[oxidation state]]. Calcium compounds are colorless. Most calcium compounds are not toxic. They are needed in the human body, actually. They are unreactive as far as calcium ions go. Calcium oxide was used to make [[limelight]]s, which have a flame heating calcium oxide and makes it glow very bright.
Calcium forms chemical compounds in the +2 [[oxidation state]]. Calcium compounds are colorless. Most calcium compounds are not toxic. They are needed in the human body, actually. They are unreactive as far as calcium ions go. Calcium oxide was used to make [[limelight]]s, which have a flame heating calcium oxide and makes it glow very bright. Forms (compounds) of calcium include:
*[[Calcium bromate]]
*[[Calcium bromate]]
*[[Calcium carbonate]]
*[[Calcium carbonate]] (used in medications and [[construction]])
*[[Calcium chloride]]
**Calcium bicarbonate (causes [[limescale]], such as on [[kitchen]] and [[bathroom]] appliances)
*[[Calcium hydroxide]]
*Calcium citrate (used in medications)
*[[Calcium nitrate]]
*[[Calcium sulfate|Calcium sulphate]] (also called gypsum, used in brewery and construction)
*[[Calcium nitride]]
*[[Calcium chloride]] (used in medical [[Therapy|treatments]] and food processing)
*[[Calcium oxide]]
*[[Calcium hydroxide]] (used in construction, food processing, and water treatment)
*[[Calcium permanganate]]
*[[Calcium nitrate]] (used in agriculture)
*[[Calcium phosphate]]
*[[Calcium nitride]] (used in chemistry and making [[LED]] lights)
*[[Calcium oxide]] (used in water treatment and metal ([[steel]]) work)
**[[Calcium oxalate]] (found in plants for example in [[Urtica dioica|stinging nettle]] during the winter, when it is flowering)
*[[Calcium permanganate]] (used in water treatment, as a disinfectant and for sterilizing)
*[[Calcium phosphate]] (used in medicine, calcium phosphate compounds are used in making [[wine]])
*[[Dicalcium phosphate]]
*[[Dicalcium phosphate]]
*[[Monocalcium phosphate]]
*[[Monocalcium phosphate]] (used in baking, animal feed and fertilizers)
<gallery>
<gallery>
File:Dusičnan vápenatý.JPG|Calcium nitrate
File:Dusičnan vápenatý.JPG|Calcium nitrate
</gallery>
</gallery>
== Isotopes ==
== Isotopes of calcium ==
Calcium has 6 naturally occurring isotopes (<sup>40</sup>Ca, <sup>42</sup>Ca, <sup>43</sup>Ca, <sup>44</sup>Ca, <sup>46</sup>Ca and <sup>48</sup>Ca), of which <sup>48</sup>Ca is very slightly radioactive with a [[half-life]] about 6.4×10<sup>19</sup> years.<ref name=Arnold2016>{{Cite journal
Calcium has 6 naturally occurring isotopes (<sup>40</sup>Ca, <sup>42</sup>Ca, <sup>43</sup>Ca, <sup>44</sup>Ca, <sup>46</sup>Ca and <sup>48</sup>Ca), of which <sup>48</sup>Ca is very slightly radioactive with a [[half-life]] about 6.4×10<sup>19</sup> years.<ref name="Arnold2016">{{Cite journal
|last1=Arnold |first1=R.
|last1=Arnold |first1=R.
|display-authors=etal
|display-authors=etal
|doi= 10.1103/PhysRevD.93.112008
|doi= 10.1103/PhysRevD.93.112008
|arxiv=1604.01710|bibcode=2016PhRvD..93k2008A|s2cid=55485404
|arxiv=1604.01710|bibcode=2016PhRvD..93k2008A|s2cid=55485404
}}</ref> Traces of <sup>41</sup>Ca, <sup>45</sup>Ca and <sup>47</sup>Ca are made by cosmic rays striking atoms, and are called [[cosmogenic nuclide]]s. <sup>41</sup>Ca is made by the neutron activation of <sup>40</sup>Ca in the upper layers of the Earth's crust and has a half-life of 102,000 years. Since it decays to potassium-41, it is a critical indicator of [[solar system]] anomalies.
}}</ref> Traces of <sup>41</sup>Ca, <sup>45</sup>Ca and <sup>47</sup>Ca are made by cosmic rays striking atoms, and are called [[cosmogenic nuclide]]s. <sup>41</sup>Ca is made by the neutron activation of <sup>40</sup>Ca in the upper layers of the Earth's crust and has a half-life of 102,000 years. Since it [[Decay product|decays]] to [[potassium-41]], it is a critical indicator of [[solar system]] anomalies.
Calcium-40 is the most abundant isotope (96% of all natural calcium), since it comes from radiogenic <sup>40</sup>K, which has a half-life of 1.25 billion years. However, along with calcium-46, it is theoretically unstable but with a half-life so long it has never been observed to decay.
Calcium-40 is the most abundant isotope (96% of all natural calcium), since it comes from radiogenic <sup>40</sup>K, which has a half-life of 1.25 billion years. However, along with calcium-46, it is theoretically unstable but with a half-life so long it has never been observed to decay.
== Occurrence ==
== Purpose and use ==
{{See also|Geology|}}
Calcium is found in high amounts in [[soil]], especially when the soil has been made from [[Rock (geology)|rocks]] high in the different calcium forms. It can be deposited into the soil over time by leaching and deposition. It comes from [[rainfall]] and leaching out of the atmosphere, and it probably plays a role in the [[water cycle]] (or rain cycle). Because calcium is so porous (which means water can go through it), the soil could use it on some layer as a natural filter. Leaching also causes calcium to go from the rain into human drinking water in some parts of the world, and causes "hard" drinking water, in places where there is a lot of calcium in the environment and water.
== Humans ==
{{Main|Calcium (diet)}}
When calcium is mixed into building materials in the right form and concentration, it makes [[Building|buildings]] stronger and more resistant to [[weather]]. Calcium is used by humans in [[construction]] (as limestone, or [[calcium carbonate]]) to make [[concrete]] and [[Brick|bricks]] better for building with, and gypsum ([[calcium sulfate]]) as a plaster.<ref>{{Cite web|url=https://pubs.usgs.gov/sir/2017/5118/elements/Calcium/Ca_txt.html|access-date=2026-04-11|website=pubs.usgs.gov}}</ref>
In [[brewery]] (making [[Alcohol (drug)|alcohol]]) gypsum is used and is the good one. Gypsum (calcium sulphate) is the good mineral because it does not break down with boiling, which alcohol needs. Chalk ([[Calcium carbonate|calcium bicarbonate]]) is the bad form to use in brewery because it does break down, deposits limescale on the equipment and brings out the "harsher characteristics" of the [[hops]] as well as its ions interacting negatively with the [[fermentation]] process.<ref>{{Cite book|title=Home brewing: a guide to making your own beer, wine and cider|last=Bruning|first=Ted|date=2011|publisher=National Trust|isbn=978-1-907892-03-5|location=London}}</ref>
Humans (and other animals) use calcium to maintain or grow healthy bones and [[Tooth|teeth]].<ref name=":2" /> Calcium is used in the body where electricity is used, like in the muscles and nerves. Calcium is useful for animals and humans, and is found in nature. [[Cow]] milk is rich in calcium and other nutrients so that baby cows drinking it from their mother can grow up healthy and strong.
[[File:Calcite-cu01abg.jpg|thumb|Calcite]]
== Other uses ==
Calcium is not found as a metal in the ground; it is too reactive.<ref>{{cite web|title=Calcium: the essentials|url=http://www.webelements.com/calcium/|publisher=WebElements|accessdate=7 February 2016}}</ref> [[Calcium carbonate]], also known as [[calcite]], is the most common calcium mineral.
As an [[element]], calcium is used in the [[reduction (chemistry)|reduction]] of other metals. It can also be used to make [[Alloy|alloys]] (metal mix) with other metals.
== Calcium in cells ==
== As chemical compounds ==
[[File:Concrete pouring 0020.jpg|thumb|right|Concrete used to make a building]]
Calcium compounds are also important in [[chemistry]]. It is important for making things. It is a part of [[cement]] which is needed to make [[concrete]] (a hard substance that many buildings are made from.)
Calcium ions are important to cells, but too many calcium ions can be bad. If a cell gets more calcium ion than it needs, it can die. This is why the amount of calcium ion in cells is highly regulated. Conversely, not enough calcium ion is bad. Cells must have the right amount to function properly.
Calcium is part of [[calcium oxide]]. Calcium oxide is used to make [[paper]], [[pottery]], food, and to purify water (make it good to drink.) Calcium carbonate is used as a calcium supplement. Calcium permanganate can be used as a rocket [[propellant|propellant]].
{{Anchor|supplements}}
== Calcium Supplements ==
{{See also|Calcium (diet)|label 1=}}
Calcium is very important for the human body.
Calcium is used in supplements a lot to increase the size of the tablet (as a bulking agent), for example 500mg of calcium added to in [[vitamin D]] tablets<ref>[https://bnf.nice.org.uk/drugs/colecalciferol-with-calcium-carbonate/#:~:text=Prescribing%20and%20dispensing%20information%20For,details%20of%20other%20available%20products. https://bnf.nice.org.uk/drugs/colecalciferol-with-calcium-carbonate/#:~:text=Prescribing%20and%20dispensing%20information%20For,details%20of%20other%20available%20products.]</ref> or other [[vitamin]] supplements. Usually it is in the form of calcium carbonate or calcium citrate. Calcium is added to some [[Medication|medications]] such as over-the-counter (OTC) [[antacid]] products (used to neutralize [[Stomach ache|stomach acid]]). Calcium has the ability to neutralize stomach acid and some products (like [[Tums]] and Rolands, in America) have added calcium in the form of calcium carbonate.<ref name=":3">{{Cite web|title=Office of Dietary Supplements - Calcium|url=https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/|access-date=2026-04-12|website=ods.od.nih.gov|language=en}}</ref> The calcium content depends on the antacid product strength and can range from 270-400mg of calcium.<ref name=":3" />
== Calcium storage ==
[[Bone]]s contain most of the calcium ion in the human body. If we need more calcium for our [[blood]], [[muscles]], or other [[tissue (biological)|tissue]], it comes from the bones. If we have extra calcium it goes into bones.
Calcium as an element is not found in the human body, just calcium ions in the form of [[chemical compound]]s.
[[Calcium supplements]] exist and taking less than 1,500mg a day is probably not going to cause harm.<ref name=":2" /> Taking too much calcium in [[Dietary supplement|supplement form]] might damage the body, and a balanced, [[Healthy diet|varied diet]] is usually enough to get all of the calcium the [[body]] needs. Supplements are taken with food.<ref name=":5">{{Cite web|title=Calcium|url=https://www.drugs.com/cdi/calcium.html|url-status=live|archive-url=|website=drugs.com}}</ref>
== Calcium regulation ==
Some people have [[Adverse effect (medicine)|adverse reactions]] to calcium supplements, or more rarely, [[Allergic reaction|allergic reactions]]. Signs of adverse effects from calcium supplements (or [[Hypercalcemia|hypercalcaemia]]) include feeling [[Fatigue|tired]], [[Confusion|confused]], [[headache]], an upset stomach (or [[tummy ache]]), [[constipation]] and [[Vomiting|throwing up]].<ref name=":5" /> Calcium can cause bone pain in high amounts or as an allergic or adverse reaction.<ref name=":5" />.
== Use in the body ==
{{See also|Calcium (diet)}}
Calcium<ref>{{Cite web|title=MeSH Browser|url=https://meshb.nlm.nih.gov/record/ui?ui=D002118|access-date=2026-04-09|website=meshb.nlm.nih.gov}}</ref> as an element is not found in the [[human body]], just calcium ions in the form of [[chemical compound|chemical compounds]]. In this form it is used in the body. People usually get enough calcium from the [[Diet (nutrition)|diet]].<ref name=":2">{{Cite web|date=2017-10-23|title=Vitamins and minerals - Calcium|url=https://www.nhs.uk/conditions/vitamins-and-minerals/calcium/|access-date=2026-04-09|website=nhs.uk|language=en}}</ref> [[Adult]] humans (aged 19 to 64) need around 700mg of calcium daily.<ref name=":2" /> Calcium is used throughout the human body,<ref name=":2" /> used in most muscles. Taking 1,500mg of calcium (usually as a supplement in these amounts) is unlikely to cause harm.<ref name=":2" />
Dietary calcium comes from [[milk]] and [[Dairy product|dairy products]] or soya drinks with added calcium, [[fish]] where eating them includes the bones (for example, [[Sardine|sardines]]), and green, leafy [[Vegetable|vegetables]].<ref name=":2" /> Vegetables that are high in calcium include [[Kale|curly kale]] and [[okra]], but not [[spinach]] (which does contain a lot of calcium but it is not useful for the body).<ref name=":2" /> Fortified [[flour]] which makes [[bread]] (called [[Fortification|fortified]] food) might be a source of calcium or other the fortifying additives (such as niacin or [[vitamin B3]]) it contains.
== Preparation ==
== Preparation ==
Calcium metal is made by [[electrolysis]] of melted [[calcium chloride]]. It has to be very hot to melt it. The calcium metal is liquid.
Calcium metal is made by [[electrolysis]], usually with melted [[calcium chloride]] in a molten salt bath. It has to be very hot to melt it. The reaction occurs in the range of 650 to 750 degrees celsius (C)<ref name=":0">{{Cite patent|number=US3226311A|title=Process of producing calcium by electrolysis|gdate=1965-12-28|invent1=Diest|inventor1-first=Jacques Van|url=https://patents.google.com/patent/US3226311A/en}}</ref> (around 1200 to 1560 degrees fahrenheit). Sometimes, additives are used to lower the boiling point of the metal. This is because pure calcium chloride melts at around 772 C, or calcium chloride melts in the range of 772 to 782 degrees celsius.<ref>{{Cite web|last=PubChem|title=Calcium Chloride|url=https://pubchem.ncbi.nlm.nih.gov/compound/5284359|access-date=2026-04-09|website=pubchem.ncbi.nlm.nih.gov|language=en}}</ref>
== Uses ==
== As an element ==
== As chemical compounds ==
Potassium chloride can be used as an additive for the preparation of calcium chloride via electrolysis. It make the extraction more efficient by lowering its boiling point. The amount of potassium added to the molten salt bath can range from 15 to 35 percent (with 75 percent calcium chloride), with 10 percent being the minimum or 25 percent being preferred.<ref name=":0" />
== Safety ==
== Safety ==
Calcium is toxic as an element. It reacts with water and makes a strong [[base (chemistry)|base]], calcium hydroxide. Calcium compounds are not toxic unless the [[anion]] is toxic. Calcium permanganate is only toxic because of the [[permanganate]], not the calcium. Like other [[alkaline earth metal]]s calcium burns easily and brightly.
Calcium is [[Poison|toxic]] as an element. It reacts with water and makes a strong [[base (chemistry)|base]], calcium hydroxide. Calcium compounds are not toxic unless the [[anion]] is toxic. [[Calcium permanganate]] is only toxic because of the [[permanganate]], not the calcium. Like other [[alkaline earth metal]]s calcium [[Burning|burns]] easily and brightly.
== Calcium Media ==
== Calcium Media ==
== Related pages ==
== Related pages ==
*[[Calcium compounds]]
*[[Calcium compounds]]
== Sources ==
* [[Potassium]], [[sodium]] (other minerals with salt and metal forms) and [[zinc]]
* [[Hypercalcemia]], or too much calcium in the blood, and [[hyperkalemia]], too much potassium in the blood
== References ==
{{Reflist}}
{{Reflist}}
{{Periodic Table}}
{{Periodic Table}}