Difference between revisions of "Strontium"
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==Properties== | ==Properties== | ||
===Chemical=== | ===Chemical=== | ||
| − | 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. | + | 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. | 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. | ||
| Line 295: | Line 295: | ||
==Projects== | ==Projects== | ||
*Colored flames | *Colored flames | ||
| − | * | + | *Make strontium titanate |
| + | *Make strontium salts | ||
==Handling== | ==Handling== | ||
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===Disposal=== | ===Disposal=== | ||
| − | 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. | + | 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. |
==References== | ==References== | ||
Latest revision as of 17:51, 14 December 2017
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| General properties | |||||
|---|---|---|---|---|---|
| Name, symbol | Strontium, Sr | ||||
| Appearance | Silvery-white | ||||
| Strontium in the periodic table | |||||
| |||||
| Atomic number | 38 | ||||
| Standard atomic weight (Ar) | 87.62(1) | ||||
| Group, block | (alkaline earth metals); s-block | ||||
| Period | period 5 | ||||
| Electron configuration | [Kr] 5s2 | ||||
per shell | 2, 8, 18, 8, 2 | ||||
| Physical properties | |||||
| Silvery-white | |||||
| Phase | Solid | ||||
| 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) | ||||
| pressure | |||||
| Atomic properties | |||||
| Oxidation states | 2, 1 (a strongly basic oxide) | ||||
| Electronegativity | Pauling scale: 0.95 | ||||
| energies |
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 | ||||
| Miscellanea | |||||
| Crystal structure | | ||||
| 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) | ||||
| Magnetic ordering | Paramagnetic | ||||
| Young's modulus | 15.7 GPa | ||||
| Shear modulus | 6.03 GPa | ||||
| Poisson ratio | 0.28 | ||||
| Mohs hardness | 1.5 | ||||
| CAS Registry Number | 7440-24-6 | ||||
| History | |||||
| 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.
Contents
Properties
Chemical
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.
Physical
Strontium metal is soft and silvery. Its salts tend to produce a scarlet-red flame when burned in a flame.
Availability
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.
Preparation
Strontium is difficult to prepare and cheap to buy, so it is worth just buying the metal.
Projects
- Colored flames
- Make strontium titanate
- Make strontium salts
Handling
Safety
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.
Storage
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.
Disposal
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.
