Difference between revisions of "Calcium"
| Line 19: | Line 19: | ||
|alt names= | |alt names= | ||
|allotropes= | |allotropes= | ||
| − | |appearance= | + | |appearance=Silvery-gray |
<!-- Periodic table --> | <!-- Periodic table --> | ||
| − | |above= | + | |above=[[Magnesium|Mg]] |
| − | |below= | + | |below=[[Strontium|Sr]] |
| − | |left= | + | |left=[[Potassium]] |
| − | |right= | + | |right=[[Scandium]] |
| − | |number= | + | |number=20 |
| − | |atomic mass= | + | |atomic mass=40.078(4) |
|atomic mass 2= | |atomic mass 2= | ||
|atomic mass ref= | |atomic mass ref= | ||
| Line 34: | Line 34: | ||
|series comment= | |series comment= | ||
|series color= | |series color= | ||
| − | |group= | + | |group=2 |
|group ref= | |group ref= | ||
| − | |group comment= | + | |group comment=(alkaline earth metals) |
| − | |period= | + | |period=4 |
|period ref= | |period ref= | ||
|period comment= | |period comment= | ||
| − | |block= | + | |block=s |
|block ref= | |block ref= | ||
|block comment= | |block comment= | ||
| − | |electron configuration= | + | |electron configuration=[Ar] 4s<sup>2</sup> |
|electron configuration ref= | |electron configuration ref= | ||
|electron configuration comment= | |electron configuration comment= | ||
| − | |electrons per shell= | + | |electrons per shell=2, 8, 8, 2 |
|electrons per shell ref= | |electrons per shell ref= | ||
|electrons per shell comment= | |electrons per shell comment= | ||
| Line 52: | Line 52: | ||
|physical properties comment= | |physical properties comment= | ||
|color=Silvery-gray | |color=Silvery-gray | ||
| − | |phase= | + | |phase=Solid |
|phase ref= | |phase ref= | ||
|phase comment= | |phase comment= | ||
| − | |melting point K= | + | |melting point K=1115 |
| − | |melting point C= | + | |melting point C=842 |
| − | |melting point F= | + | |melting point F=1548 |
|melting point ref= | |melting point ref= | ||
|melting point comment= | |melting point comment= | ||
| − | |boiling point K= | + | |boiling point K=1757 |
| − | |boiling point C= | + | |boiling point C=1484 |
| − | |boiling point F= | + | |boiling point F=2703 |
|boiling point ref= | |boiling point ref= | ||
|boiling point comment= | |boiling point comment= | ||
| Line 73: | Line 73: | ||
|density gplstp ref= | |density gplstp ref= | ||
|density gplstp comment= | |density gplstp comment= | ||
| − | |density gpcm3nrt= | + | |density gpcm3nrt=1.55 |
|density gpcm3nrt ref= | |density gpcm3nrt ref= | ||
|density gpcm3nrt comment= | |density gpcm3nrt comment= | ||
| Line 82: | Line 82: | ||
|density gpcm3nrt 3 ref= | |density gpcm3nrt 3 ref= | ||
|density gpcm3nrt 3 comment= | |density gpcm3nrt 3 comment= | ||
| − | |density gpcm3mp= | + | |density gpcm3mp=1.378 |
|density gpcm3mp ref= | |density gpcm3mp ref= | ||
|density gpcm3mp comment= | |density gpcm3mp comment= | ||
| Line 104: | Line 104: | ||
|critical point ref= | |critical point ref= | ||
|critical point comment= | |critical point comment= | ||
| − | |heat fusion= | + | |heat fusion=8.54 |
|heat fusion ref= | |heat fusion ref= | ||
|heat fusion comment= | |heat fusion comment= | ||
| Line 110: | Line 110: | ||
|heat fusion 2 ref= | |heat fusion 2 ref= | ||
|heat fusion 2 comment= | |heat fusion 2 comment= | ||
| − | |heat vaporization= | + | |heat vaporization=154.7 |
|heat vaporization ref= | |heat vaporization ref= | ||
|heat vaporization comment= | |heat vaporization comment= | ||
| − | |heat capacity= | + | |heat capacity=25.929 |
|heat capacity ref= | |heat capacity ref= | ||
|heat capacity comment= | |heat capacity comment= | ||
| Line 119: | Line 119: | ||
|heat capacity 2 ref= | |heat capacity 2 ref= | ||
|heat capacity 2 comment= | |heat capacity 2 comment= | ||
| − | |vapor pressure 1= | + | |vapor pressure 1=864 |
| − | |vapor pressure 10= | + | |vapor pressure 10=956 |
| − | |vapor pressure 100= | + | |vapor pressure 100=1071 |
| − | |vapor pressure 1 k= | + | |vapor pressure 1 k=1227 |
| − | |vapor pressure 10 k= | + | |vapor pressure 10 k=1443 |
| − | |vapor pressure 100 k= | + | |vapor pressure 100 k=1755 |
|vapor pressure ref= | |vapor pressure ref= | ||
|vapor pressure comment= | |vapor pressure comment= | ||
| Line 137: | Line 137: | ||
<!-- Atomic properties --> | <!-- Atomic properties --> | ||
|atomic properties comment= | |atomic properties comment= | ||
| − | |oxidation states= | + | |oxidation states='''+2''', +1 |
|oxidation states ref= | |oxidation states ref= | ||
| − | |oxidation states comment= | + | |oxidation states comment=(a strongly basic oxide) |
| − | |electronegativity= | + | |electronegativity=1.00 |
|electronegativity ref= | |electronegativity ref= | ||
|electronegativity comment= | |electronegativity comment= | ||
| − | |ionization energy 1= | + | |ionization energy 1=589.8 |
|ionization energy 1 ref= | |ionization energy 1 ref= | ||
|ionization energy 1 comment= | |ionization energy 1 comment= | ||
| − | |ionization energy 2= | + | |ionization energy 2=1145.4 |
|ionization energy 2 ref= | |ionization energy 2 ref= | ||
|ionization energy 2 comment= | |ionization energy 2 comment= | ||
| − | |ionization energy 3= | + | |ionization energy 3=4912.4 |
|ionization energy 3 ref= | |ionization energy 3 ref= | ||
|ionization energy 3 comment= | |ionization energy 3 comment= | ||
| Line 155: | Line 155: | ||
|ionization energy ref= | |ionization energy ref= | ||
|ionization energy comment= | |ionization energy comment= | ||
| − | |atomic radius= | + | |atomic radius=197 |
|atomic radius ref= | |atomic radius ref= | ||
|atomic radius comment= | |atomic radius comment= | ||
| Line 161: | Line 161: | ||
|atomic radius calculated ref= | |atomic radius calculated ref= | ||
|atomic radius calculated comment= | |atomic radius calculated comment= | ||
| − | |covalent radius= | + | |covalent radius=176±10 |
|covalent radius ref= | |covalent radius ref= | ||
|covalent radius comment= | |covalent radius comment= | ||
| − | |Van der Waals radius= | + | |Van der Waals radius=231 |
|Van der Waals radius ref= | |Van der Waals radius ref= | ||
|Van der Waals radius comment= | |Van der Waals radius comment= | ||
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|crystal structure prefix= | |crystal structure prefix= | ||
|crystal structure ref= | |crystal structure ref= | ||
| − | |crystal structure comment= | + | |crystal structure comment=Face-centred cubic (fcc) |
|crystal structure 2= | |crystal structure 2= | ||
|crystal structure 2 prefix= | |crystal structure 2 prefix= | ||
| Line 179: | Line 179: | ||
|speed of sound ref= | |speed of sound ref= | ||
|speed of sound comment= | |speed of sound comment= | ||
| − | |speed of sound rod at 20= | + | |speed of sound rod at 20=3810 |
|speed of sound rod at 20 ref= | |speed of sound rod at 20 ref= | ||
|speed of sound rod at 20 comment= | |speed of sound rod at 20 comment= | ||
| Line 188: | Line 188: | ||
|thermal expansion ref= | |thermal expansion ref= | ||
|thermal expansion comment= | |thermal expansion comment= | ||
| − | |thermal expansion at 25= | + | |thermal expansion at 25=22.3 |
|thermal expansion at 25 ref= | |thermal expansion at 25 ref= | ||
|thermal expansion at 25 comment= | |thermal expansion at 25 comment= | ||
| − | |thermal conductivity= | + | |thermal conductivity=201 |
|thermal conductivity ref= | |thermal conductivity ref= | ||
|thermal conductivity comment= | |thermal conductivity comment= | ||
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|electrical resistivity at 0 ref= | |electrical resistivity at 0 ref= | ||
|electrical resistivity at 0 comment= | |electrical resistivity at 0 comment= | ||
| − | |electrical resistivity at 20= | + | |electrical resistivity at 20=33.6·10<sup>-9</sup> |
|electrical resistivity at 20 ref= | |electrical resistivity at 20 ref= | ||
|electrical resistivity at 20 comment= | |electrical resistivity at 20 comment= | ||
| Line 216: | Line 216: | ||
|Curie point ref= | |Curie point ref= | ||
|Curie point comment= | |Curie point comment= | ||
| − | |magnetic ordering= | + | |magnetic ordering=Diamagnetic |
|magnetic ordering ref= | |magnetic ordering ref= | ||
|magnetic ordering comment= | |magnetic ordering comment= | ||
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|tensile strength ref= | |tensile strength ref= | ||
|tensile strength comment= | |tensile strength comment= | ||
| − | |Young's modulus= | + | |Young's modulus=20 |
|Young's modulus ref= | |Young's modulus ref= | ||
|Young's modulus comment= | |Young's modulus comment= | ||
| − | |Shear modulus= | + | |Shear modulus=7.4 |
|Shear modulus ref= | |Shear modulus ref= | ||
|Shear modulus comment= | |Shear modulus comment= | ||
| − | |Bulk modulus= | + | |Bulk modulus=17 |
|Bulk modulus ref= | |Bulk modulus ref= | ||
|Bulk modulus comment= | |Bulk modulus comment= | ||
| − | |Poisson ratio= | + | |Poisson ratio=0.31 |
|Poisson ratio ref= | |Poisson ratio ref= | ||
|Poisson ratio comment= | |Poisson ratio comment= | ||
| − | |Mohs hardness= | + | |Mohs hardness=1.75 |
|Mohs hardness ref= | |Mohs hardness ref= | ||
|Mohs hardness comment= | |Mohs hardness comment= | ||
| Line 243: | Line 243: | ||
|Vickers hardness ref= | |Vickers hardness ref= | ||
|Vickers hardness comment= | |Vickers hardness comment= | ||
| − | |Brinell hardness= | + | |Brinell hardness=170–416 |
|Brinell hardness ref= | |Brinell hardness ref= | ||
|Brinell hardness comment= | |Brinell hardness comment= | ||
| − | |CAS number= | + | |CAS number=7440-70-2 |
|CAS number ref= | |CAS number ref= | ||
|CAS number comment= | |CAS number comment= | ||
| Line 260: | Line 260: | ||
|first isolation date ref= | |first isolation date ref= | ||
|first isolation date= | |first isolation date= | ||
| − | |discovery and first isolation by= | + | |discovery and first isolation by=Humphry Davy (1808) |
|named by= | |named by= | ||
|named date ref= | |named date ref= | ||
Revision as of 21:13, 8 October 2017
 Calcium metal under argon. | |||||
| General properties | |||||
|---|---|---|---|---|---|
| Name, symbol | Calcium, Ca | ||||
| Appearance | Silvery-gray | ||||
| Calcium in the periodic table | |||||
| |||||
| Atomic number | 20 | ||||
| Standard atomic weight (Ar) | 40.078(4) | ||||
| Group, block | (alkaline earth metals); s-block | ||||
| Period | period 4 | ||||
| Electron configuration | [Ar] 4s2 | ||||
per shell | 2, 8, 8, 2 | ||||
| Physical properties | |||||
| Silvery-gray | |||||
| Phase | Solid | ||||
| Melting point | 1115 K (842 °C, 1548 °F) | ||||
| Boiling point | 1757 K (1484 °C, 2703 °F) | ||||
| Density near r.t. | 1.55 g/cm3 | ||||
| when liquid, at | 1.378 g/cm3 | ||||
| Heat of fusion | 8.54 kJ/mol | ||||
| Heat of | 154.7 kJ/mol | ||||
| Molar heat capacity | 25.929 J/(mol·K) | ||||
| pressure | |||||
| Atomic properties | |||||
| Oxidation states | +2, +1 (a strongly basic oxide) | ||||
| Electronegativity | Pauling scale: 1.00 | ||||
| energies |
1st: 589.8 kJ/mol 2nd: 1145.4 kJ/mol 3rd: 4912.4 kJ/mol | ||||
| Atomic radius | empirical: 197 pm | ||||
| Covalent radius | 176±10 pm | ||||
| Van der Waals radius | 231 pm | ||||
| Miscellanea | |||||
| Crystal structure | Face-centred cubic (fcc) | ||||
| Speed of sound thin rod | 3810 m/s (at 20 °C) | ||||
| Thermal expansion | 22.3 µm/(m·K) (at 25 °C) | ||||
| Thermal conductivity | 201 W/(m·K) | ||||
| Electrical resistivity | 33.6·10-9 Ω·m (at 20 °C) | ||||
| Magnetic ordering | Diamagnetic | ||||
| Young's modulus | 20 GPa | ||||
| Shear modulus | 7.4 GPa | ||||
| Bulk modulus | 17 GPa | ||||
| Poisson ratio | 0.31 | ||||
| Mohs hardness | 1.75 | ||||
| Brinell hardness | 170–416 MPa | ||||
| CAS Registry Number | 7440-70-2 | ||||
| Discovery and first isolation | Humphry Davy (1808) | ||||
Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust.
Contents
Properties
Chemical
Calcium is reactive towards air but is often kept in a sealed container as opposed to under oil as its oxidation is not excessively rapid. As pellets or turnings, the metal can be difficult to ignite, more so even than magnesium turnings, but when lit the metal burns in air with a brilliant red light, producing calcium oxide.
Calcium reacts with the usually inert nitrogen, forming calcium nitride. If a container of calcium is left open in a glove box full of nitrogen, the metal will quickly be ruined.
Calcium produces hydrogen on contact with water, at a noticeably slower rater than all the alkali metals when in the same from but powder calcium is much more common than any alkali metal powders, and the increased surface area of the metal produces a rapid reaction. Part of the reason for the slowness of the calcium–water reaction is a result of the metal being partly protected by insoluble white calcium hydroxide. In acids where the calcium salt is soluble, the metal reacts vigorously.
At very high temperatures (usually in an arc furnace) the metal reacts with carbon to produce the useful calcium carbide.
Physical
Calcium is a soft for a metal (though harder than lead, it can be cut with a knife with difficulty). It is a silvery metallic element with a density of 1.55 g/cm3. Calcium has the lowest density of the alkaline earth metals; magnesium (specific gravity 1.74) and beryllium (1.84) are denser though lighter in atomic mass. From strontium onward, the alkali earth metals become denser with increasing atomic mass.
Availability
Calcium can be bought at Gallium Source.
As a reducing agent, it suffers some of the stigma and restrictions sodium does because it can be used in the manufacture of illicit drugs. In Australia, purchasing calcium metal requires an EUD.
Preparation
Preparing calcium metal is not easy or economical for the amateur chemist. It can be extracted by electrolysis from a fused salt like calcium chloride. Once produced, it rapidly forms a gray-white oxide and nitride coating when exposed to air.
Projects
- Producing calcium carbide
- Make calcium nitride
- Extracting lanthanides
Handling
Safety
Compared with other metals, the calcium ion and most calcium compounds have low toxicity. This is not surprising given the very high natural abundance of calcium compounds in the environment and in organisms. Acute calcium poisoning is rare, and difficult to achieve unless calcium compounds are administered intravenously.
Calcium metal is hazardous because of it reacts violently with water and acids. Calcium metal is found in some drain cleaners, where it functions to generate heat and calcium hydroxide that saponifies the fats and liquefies the proteins (e.g., hair) that block drains. When swallowed calcium metal has the same effect on the mouth, esophagus and stomach, and can be fatal.
Storage
Large pieces of calcium metal can be stored in dry air without any severe degradation, as noted by many chemists. Turnings and calcium powder is much more reactive. Like all air-sensitive materials, calcium must be stored in sealed containers or glass ampoules, in an inert atmosphere (such as argon). It can also be stored in mineral oil.
Disposal
Calcium metal can be neutralized by slowly dissolving it in water or simply leaving it in wet air, which turns it into calcium oxide, hydroxide and finally carbonate (or sulfate/nitrate, depending on the quality of air).
As calcium compounds are abundant in the environment and pose no toxicity, no special treatment is required to dispose of them. However it is advised to avoid dumping the poorly soluble ones down the drain as they might build up and clog the pipes.
