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|Name, symbol||Strontium, Sr|
|Strontium in the periodic table|
|Standard atomic weight (Ar)||87.62(1)|
|Group, block||(alkaline earth metals); s-block|
|Electron configuration||[Kr] 5s2|
|2, 8, 18, 8, 2|
|Melting point||1050 K (777 °C, 1431 °F)|
|Boiling point||1650 K (1377 °C, 2511 °F)|
|Density near r.t.||2.64 g/cm3|
|when liquid, at||2.375 g/cm3|
|Heat of fusion||7.43 kJ/mol|
|Heat of||141 kJ/mol|
|Molar heat capacity||26.4 J/(mol·K)|
|Oxidation states||2, 1 (a strongly basic oxide)|
|Electronegativity||Pauling scale: 0.95|
1st: 549.5 kJ/mol |
2nd: 1064.2 kJ/mol
3rd: 4138 kJ/mol
|Atomic radius||empirical: 215 pm|
|Covalent radius||195±10 pm|
|Van der Waals radius||249 pm|
|Thermal expansion||22.5 µm/(m·K) (at 25 °C)|
|Thermal conductivity||35.4 W/(m·K)|
|Electrical resistivity||132·10-9 Ω·m (at 20 °C)|
|Young's modulus||15.7 GPa|
|Shear modulus||6.03 GPa|
|CAS Registry Number||7440-24-6|
|Naming||After the mineral strontianite, itself named after Strontian, Scotland|
|Discovery||William Cruickshank (1787)|
|First isolation||Humphry Davy (1808)|
Strontium is an alkaline earth metal with the symbol Sr and atomic number 39.
Strontium metal bubbles fiercely on contact with water. It burns in air to produce both strontium oxide and strontium nitride, but since it only reacts with nitrogen above 380 °C, at room temperature it will only form the oxide.
The chemistry of strontium salts is similar to barium (nigh insoluble sulfate and carbonate, soluble chloride and nitrate), so strontium salts can be used as a safer, non-toxic alternatives to barium salts when detecting sulfate ions.
Strontium metal is soft and silvery. Its salts tend to produce a scarlet-red flame when burned in a flame.
Strontium metal may be purchased at GalliumSource, at 85$/ 2.5 kg.
You can also buy celestine, a mineral of strontium consisting mainly of its sulfate, from mineral collector stores. Finely ground celestine can be subjected to the Curie reaction (lengthy boiling under reflux with sodium carbonate) to convert it to strontium carbonate, which is a useful precursor to any strontium salt.
Additionally, most red-colored road flares contain strontium in the form of the nitrate, along with elemental sulfur and a binder. This can be crystallized out of the solution for a decent yield of pure, snow-white strontium nitrate.
Strontium is difficult to prepare and cheap to buy, so it is worth just buying the metal.
- Colored flames
- Strontium titanate
Strontium salts are non-toxic. They have been investigated for positive effects on bone mass, and strontium supplements are beginning to hit the market. However, that does not imply that consuming strontium salts produced in the lab is safe.
Just like calcium and all the alkali-earth metals under it, strontium metal corrodes easily on contact with air and water and must be stored under oil or in an inert atmosphere. The metal presents a fire hazard. Class D fire extinguishers should be used with strontium fires. Water will cause a hydrogen explosion.
Strontium can be safely disposed by reacting it with water or isopropanol and doesn't pose a hazard to the environment, so no special disposal is required.