Difference between revisions of "Calcium"
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Only silicates and phosphates of calcium though form decently hard and more water resistant compounds. | Only silicates and phosphates of calcium though form decently hard and more water resistant compounds. | ||
| + | = Calclium oxoacid salts = | ||
| − | + | Most simple stable common calcium oxoacid salts compounds are: | |
* environmentally friendly | * environmentally friendly | ||
* nontoxic when ingested | * nontoxic when ingested | ||
* fireproof | * fireproof | ||
| − | + | ||
| + | (For oxoacid salts of other elements see the main article: [[Salts of oxoacids]].) | ||
| + | |||
| + | == Calcium silicates (decently hard) == | ||
| + | |||
* [https://en.wikipedia.org/wiki/Wollastonite Wollastonite] CaSiO<sub>3</sub> (Mohs 4.5-5 | Triclinic) | * [https://en.wikipedia.org/wiki/Wollastonite Wollastonite] CaSiO<sub>3</sub> (Mohs 4.5-5 | Triclinic) | ||
* There are several other stable stoichiometries of calcium silicate not found as natural mineral. See wikipedia: [https://en.wikipedia.org/wiki/Calcium_silicate Calcium silicate] | * There are several other stable stoichiometries of calcium silicate not found as natural mineral. See wikipedia: [https://en.wikipedia.org/wiki/Calcium_silicate Calcium silicate] | ||
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* Nitrocalcit Ca(NO<sub>3</sub>)<sub>2</sub>•4(H<sub>2</sub>O) (Mohs 1-2) | * Nitrocalcit Ca(NO<sub>3</sub>)<sub>2</sub>•4(H<sub>2</sub>O) (Mohs 1-2) | ||
| − | + | = Halogenides = | |
* '''[https://en.wikipedia.org/wiki/Fluorite Fluorite] CaF<sub>2</sub>''' (Mohs 4 '''by definition''' | Cubic) All other calcium halogenides are water soluble salts. | * '''[https://en.wikipedia.org/wiki/Fluorite Fluorite] CaF<sub>2</sub>''' (Mohs 4 '''by definition''' | Cubic) All other calcium halogenides are water soluble salts. | ||
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* Calcium hydride CaH<sub>2</sub> is reactive similar to calcium oxide. | * Calcium hydride CaH<sub>2</sub> is reactive similar to calcium oxide. | ||
| − | + | = Misc = | |
* [https://en.wikipedia.org/wiki/Calcium_hexaboride Calcium hexaboride] CaB<sub>6</sub> is a good ceramic | * [https://en.wikipedia.org/wiki/Calcium_hexaboride Calcium hexaboride] CaB<sub>6</sub> is a good ceramic | ||
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* Calcium titanate: [https://en.wikipedia.org/wiki/Perovskite Perovskite] CaTiO<sub>3</sub> (Mohs 5-5.5 | Orthorhombic) | * Calcium titanate: [https://en.wikipedia.org/wiki/Perovskite Perovskite] CaTiO<sub>3</sub> (Mohs 5-5.5 | Orthorhombic) | ||
| − | + | = External Links = | |
* Wikipedia: [https://en.wikipedia.org/wiki/Category:Calcium_minerals Calcium minerals] | * Wikipedia: [https://en.wikipedia.org/wiki/Category:Calcium_minerals Calcium minerals] | ||
* Wikipedia: [https://en.wikipedia.org/wiki/Category:Calcium_compounds Calcium compounds] | * Wikipedia: [https://en.wikipedia.org/wiki/Category:Calcium_compounds Calcium compounds] | ||
* Wikipedia: [https://en.wikipedia.org/wiki/Calcium_aluminates Calcium aluminates] | * Wikipedia: [https://en.wikipedia.org/wiki/Calcium_aluminates Calcium aluminates] | ||
Revision as of 08:03, 19 December 2016
Calcium as pure metal is unsuitable as building material for advanced atomically precise manufacturing since:
- as metal it has meatllic interelemental bonds that is the bonds have have low directionality
- it has weak interelemental bonds
- => diffusion jumps at low twmperatures are likely
- it is also highly electropositive and reacts strongly with oxygen and even water (this actually is less of a problem since parts can perfectly be sealed)
Just oxidizing calcium may solve the problem of weak undirected metallic bonds but the formed compound is still highly reactive. Calcium oxide CaO is commonly known as burnt lime. It strongly reacts with water to calcium hydroxide. The resulting compound calcium hydroxide is slightly water soluble (it is what makes water hard / slightly basic) and very soft. Hardly usable as building material.
- Portlandite Ca(OH)2 (Mohs 2 soft| Trigonal)
Calcium oxide does also react with carbon dioxide to calcium carbonates which (albeit still pretty soft) are a better candidate for building materials. Only silicates and phosphates of calcium though form decently hard and more water resistant compounds.
Contents
Calclium oxoacid salts
Most simple stable common calcium oxoacid salts compounds are:
- environmentally friendly
- nontoxic when ingested
- fireproof
(For oxoacid salts of other elements see the main article: Salts of oxoacids.)
Calcium silicates (decently hard)
- Wollastonite CaSiO3 (Mohs 4.5-5 | Triclinic)
- There are several other stable stoichiometries of calcium silicate not found as natural mineral. See wikipedia: Calcium silicate
- ...
Calcium phosphates (hard)
- Hydroxylapatite Ca5(PO4)3(OH) (Mohs 5 | Hexagonal)
- Fluorapatite Ca5(PO4)3F (Mohs 5 | Hexagonal)
- Chloroappatite Ca5(PO4)3Cl (Mohs 5 | Hexagonal)
Polymorphs of calcium carbonate CaCO3 (soft)
- Aragonite (Mohs 3.5-4 | Orthorhombic)
- Calcite (Mohs 3 by definition | Trigonal)
- Vaterite μ-CaCO3 (Mohs 3 | Hexagonal)
- Monohydrocalcite CaCO3·H2O
- Ikaite CaCO3·6H2O (Mohs 3 | Monoclinic)
Calcium sulfates (very soft)
- Anhydrite γ-CaSO4 (Mohs 3 | Orthorhombic)
- Gypsum CaSO4·2H2O (Mohs 2 by definition | Monoclinic)
- alpha & beta hemihydrate (CaSO4)2·H2O
Calcium nitrates (very soft and highly water soluble)
- Nitrocalcit Ca(NO3)2•4(H2O) (Mohs 1-2)
Halogenides
- Fluorite CaF2 (Mohs 4 by definition | Cubic) All other calcium halogenides are water soluble salts.
- Antarcticite CaCl2·6H2O (Mohs 2-3 | Trigonal)
- Calcium hydride CaH2 is reactive similar to calcium oxide.
Misc
- Calcium hexaboride CaB6 is a good ceramic
- calcium silicide CaSi2 is pretty stable
- Calcium carbide CaC2 strongly reacts with water (it's commonly known as carbide)
Calcium carbide may be of interest since on contact with water it releases ethyne which is due to its low hydrogen content a good resource for mechanosynthesis of diamond.
Mechanosynthetic means though will allow indepencence of crude chemical means of storage like in calcium carbide.
- Calcium titanate: Perovskite CaTiO3 (Mohs 5-5.5 | Orthorhombic)
External Links
- Wikipedia: Calcium minerals
- Wikipedia: Calcium compounds
- Wikipedia: Calcium aluminates
