Difference between revisions of "Calcium"

From Sciencemadness Wiki
Jump to: navigation, search
 
(6 intermediate revisions by the same user not shown)
Line 1: Line 1:
−
[[File:1024px-Calcium_unter_Argon_Schutzgasatmosphäre.jpg|thumb|Calcium metal under argon.]]
+
{{Infobox element
−
'''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.
+
<!-- top -->
 +
|image name=Calcium under argon atmosphere.jpg
 +
|image alt=
 +
|image size=
 +
|image name comment=Calcium metal under argon.
 +
|image name 2=
 +
|image alt 2=
 +
|image size 2=
 +
|image name 2 comment=
 +
<!-- General properties -->
 +
|name=Calcium
 +
|symbol=Ca
 +
|pronounce=
 +
|pronounce ref=
 +
|pronounce comment=
 +
|pronounce 2=
 +
|alt name=
 +
|alt names=
 +
|allotropes=
 +
|appearance=Silvery-gray
 +
<!-- Periodic table -->
 +
|above=[[Magnesium|Mg]]
 +
|below=[[Strontium|Sr]]
 +
|left=[[Potassium]]
 +
|right=[[Scandium]]
 +
|number=20
 +
|atomic mass=40.078(4)
 +
|atomic mass 2=
 +
|atomic mass ref=
 +
|atomic mass comment=
 +
|series=
 +
|series ref=
 +
|series comment=
 +
|series color=
 +
|group=2
 +
|group ref=
 +
|group comment=(alkaline earth metals)
 +
|period=4
 +
|period ref=
 +
|period comment=
 +
|block=s
 +
|block ref=
 +
|block comment=
 +
|electron configuration=[Ar] 4s<sup>2</sup>
 +
|electron configuration ref=
 +
|electron configuration comment=
 +
|electrons per shell=2, 8, 8, 2
 +
|electrons per shell ref=
 +
|electrons per shell comment=
 +
<!-- Physical properties -->
 +
|physical properties comment=
 +
|color=Silvery-gray
 +
|phase=Solid
 +
|phase ref=
 +
|phase comment=
 +
|melting point K=1115
 +
|melting point C=842
 +
|melting point F=1548
 +
|melting point ref=
 +
|melting point comment=
 +
|boiling point K=1757
 +
|boiling point C=1484
 +
|boiling point F=2703
 +
|boiling point ref=
 +
|boiling point comment=
 +
|sublimation point K=
 +
|sublimation point C=
 +
|sublimation point F=
 +
|sublimation point ref=
 +
|sublimation point comment=
 +
|density gplstp=
 +
|density gplstp ref=
 +
|density gplstp comment=
 +
|density gpcm3nrt=1.55
 +
|density gpcm3nrt ref=
 +
|density gpcm3nrt comment=
 +
|density gpcm3nrt 2=
 +
|density gpcm3nrt 2 ref=
 +
|density gpcm3nrt 2 comment=
 +
|density gpcm3nrt 3=
 +
|density gpcm3nrt 3 ref=
 +
|density gpcm3nrt 3 comment=
 +
|density gpcm3mp=1.378
 +
|density gpcm3mp ref=
 +
|density gpcm3mp comment=
 +
|density gpcm3bp=
 +
|density gpcm3bp ref=
 +
|density gpcm3bp comment=
 +
|molar volume=
 +
|molar volume unit =
 +
|molar volume ref=
 +
|molar volume comment=
 +
|triple point K=
 +
|triple point kPa=
 +
|triple point ref=
 +
|triple point comment=
 +
|triple point K 2=
 +
|triple point kPa 2=
 +
|triple point 2 ref=
 +
|triple point 2 comment=
 +
|critical point K=
 +
|critical point MPa=
 +
|critical point ref=
 +
|critical point comment=
 +
|heat fusion=8.54
 +
|heat fusion ref=
 +
|heat fusion comment=
 +
|heat fusion 2=
 +
|heat fusion 2 ref=
 +
|heat fusion 2 comment=
 +
|heat vaporization=154.7
 +
|heat vaporization ref=
 +
|heat vaporization comment=
 +
|heat capacity=25.929
 +
|heat capacity ref=
 +
|heat capacity comment=
 +
|heat capacity 2=
 +
|heat capacity 2 ref=
 +
|heat capacity 2 comment=
 +
|vapor pressure 1=864
 +
|vapor pressure 10=956
 +
|vapor pressure 100=1071
 +
|vapor pressure 1 k=1227
 +
|vapor pressure 10 k=1443
 +
|vapor pressure 100 k=1755
 +
|vapor pressure ref=
 +
|vapor pressure comment=
 +
|vapor pressure 1 2=
 +
|vapor pressure 10 2=
 +
|vapor pressure 100 2=
 +
|vapor pressure 1 k 2=
 +
|vapor pressure 10 k 2=
 +
|vapor pressure 100 k 2=
 +
|vapor pressure 2 ref=
 +
|vapor pressure 2 comment=
 +
<!-- Atomic properties -->
 +
|atomic properties comment=
 +
|oxidation states='''+2''', +1
 +
|oxidation states ref=
 +
|oxidation states comment=(a strongly basic oxide)
 +
|electronegativity=1.00
 +
|electronegativity ref=
 +
|electronegativity comment=
 +
|ionization energy 1=589.8
 +
|ionization energy 1 ref=
 +
|ionization energy 1 comment=
 +
|ionization energy 2=1145.4
 +
|ionization energy 2 ref=
 +
|ionization energy 2 comment=
 +
|ionization energy 3=4912.4
 +
|ionization energy 3 ref=
 +
|ionization energy 3 comment=
 +
|number of ionization energies=
 +
|ionization energy ref=
 +
|ionization energy comment=
 +
|atomic radius=197
 +
|atomic radius ref=
 +
|atomic radius comment=
 +
|atomic radius calculated=
 +
|atomic radius calculated ref=
 +
|atomic radius calculated comment=
 +
|covalent radius=176±10
 +
|covalent radius ref=
 +
|covalent radius comment=
 +
|Van der Waals radius=231
 +
|Van der Waals radius ref=
 +
|Van der Waals radius comment=
 +
<!-- Miscellanea -->
 +
|crystal structure=
 +
|crystal structure prefix=
 +
|crystal structure ref=
 +
|crystal structure comment=Face-centred cubic (fcc)
 +
|crystal structure 2=
 +
|crystal structure 2 prefix=
 +
|crystal structure 2 ref=
 +
|crystal structure 2 comment=
 +
|speed of sound=
 +
|speed of sound ref=
 +
|speed of sound comment=
 +
|speed of sound rod at 20=3810
 +
|speed of sound rod at 20 ref=
 +
|speed of sound rod at 20 comment=
 +
|speed of sound rod at r.t.=
 +
|speed of sound rod at r.t. ref=
 +
|speed of sound rod at r.t. comment=
 +
|thermal expansion=
 +
|thermal expansion ref=
 +
|thermal expansion comment=
 +
|thermal expansion at 25=22.3
 +
|thermal expansion at 25 ref=
 +
|thermal expansion at 25 comment=
 +
|thermal conductivity=201
 +
|thermal conductivity ref=
 +
|thermal conductivity comment=
 +
|thermal conductivity 2=
 +
|thermal conductivity 2 ref=
 +
|thermal conductivity 2 comment=
 +
|thermal diffusivity=
 +
|thermal diffusivity ref=
 +
|thermal diffusivity comment=
 +
|electrical resistivity=
 +
|electrical resistivity unit prefix=
 +
|electrical resistivity ref=
 +
|electrical resistivity comment=
 +
|electrical resistivity at 0=
 +
|electrical resistivity at 0 ref=
 +
|electrical resistivity at 0 comment=
 +
|electrical resistivity at 20=33.6·10<sup>-9</sup>
 +
|electrical resistivity at 20 ref=
 +
|electrical resistivity at 20 comment=
 +
|band gap=
 +
|band gap ref=
 +
|band gap comment=
 +
|Curie point K=
 +
|Curie point ref=
 +
|Curie point comment=
 +
|magnetic ordering=Diamagnetic
 +
|magnetic ordering ref=
 +
|magnetic ordering comment=
 +
|tensile strength=
 +
|tensile strength ref=
 +
|tensile strength comment=
 +
|Young's modulus=20
 +
|Young's modulus ref=
 +
|Young's modulus comment=
 +
|Shear modulus=7.4
 +
|Shear modulus ref=
 +
|Shear modulus comment=
 +
|Bulk modulus=17
 +
|Bulk modulus ref=
 +
|Bulk modulus comment=
 +
|Poisson ratio=0.31
 +
|Poisson ratio ref=
 +
|Poisson ratio comment=
 +
|Mohs hardness=1.75
 +
|Mohs hardness ref=
 +
|Mohs hardness comment=
 +
|Mohs hardness 2=
 +
|Mohs hardness 2 ref=
 +
|Mohs hardness 2 comment=
 +
|Vickers hardness=
 +
|Vickers hardness ref=
 +
|Vickers hardness comment=
 +
|Brinell hardness=170–416
 +
|Brinell hardness ref=
 +
|Brinell hardness comment=
 +
|CAS number=7440-70-2
 +
|CAS number ref=
 +
|CAS number comment=
 +
<!-- History -->
 +
|naming=
 +
|predicted by=
 +
|prediction date ref=
 +
|prediction date=
 +
|discovered by=
 +
|discovery date ref=
 +
|discovery date=
 +
|first isolation by=
 +
|first isolation date ref=
 +
|first isolation date=
 +
|discovery and first isolation by=Humphry Davy (1808)
 +
|named by=
 +
|named date ref=
 +
|named date=
 +
|history comment label=
 +
|history comment=
 +
<!-- Isotopes -->
 +
|isotopes=
 +
|isotopes comment=
 +
|engvar=
 +
}}
 +
'''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.
  
 
==Properties==
 
==Properties==
 
===Chemical===
 
===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 it 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 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 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.
Line 10: Line 281:
 
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.
 
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]].
+
At very high temperatures (usually in an [[electric arc furnace]]) the metal reacts with carbon to produce the useful [[calcium carbide]].
  
 
===Physical===
 
===Physical===
Line 18: Line 289:
 
Calcium can be bought at [http://www.mcssl.com/store/gallium-source/013---calcium-metal Gallium Source].
 
Calcium can be bought at [http://www.mcssl.com/store/gallium-source/013---calcium-metal 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.
+
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==
 
==Preparation==
Line 24: Line 295:
  
 
==Projects==
 
==Projects==
−
*Producing [[calcium carbide]]
+
*Preparation of [[calcium carbide]]
 +
*Make calcium nitride
 
*Extracting lanthanides
 
*Extracting lanthanides
  
Line 37: Line 309:
  
 
===Disposal===
 
===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).
+
Calcium metal can be neutralized by slowly dissolving it in water or simply leaving it in wet air, which causes it into calcium oxide, hydroxide and finally carbonate (or sulfate/nitrate, depending on the quality of air). Granular Ca metal degrades much faster than bulk metal.
  
 
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.
 
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.
Line 52: Line 324:
 
[[Category:Materials unstable in acidic solution]]
 
[[Category:Materials unstable in acidic solution]]
 
[[Category:Materials that react with water]]
 
[[Category:Materials that react with water]]
 +
[[Category:Air-sensitive materials]]
 
[[Category:S-block]]
 
[[Category:S-block]]

Latest revision as of 15:50, 22 December 2022

Calcium,  20Ca
Calcium under argon atmosphere.jpg
Calcium metal under argon.
General properties
Name, symbol Calcium, Ca
Appearance Silvery-gray
Calcium in the periodic table
Mg
↑
Ca
↓
Sr
Potassium ← Calcium → Scandium
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)
· references

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.

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 electric 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

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 causes it into calcium oxide, hydroxide and finally carbonate (or sulfate/nitrate, depending on the quality of air). Granular Ca metal degrades much faster than bulk metal.

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.

References

Relevant Sciencemadness threads

Retrieved from "https://www.sciencemadness.org/smwiki/index.php?title=Calcium&oldid=14839"