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Oxidation & Electrons | Appearance & Characteristics Reactions | Compounds | Radius | Conductivity Abundance & Isotopes 
Strontium (Photo: Matthias Zepper) |
General:
| Name: Strontium | Symbol: Sr |
| Type: Alkali Earth Metal | Atomic weight: 87.62 |
| Density @ 293 K: 2.6 g/cm3 | Atomic volume: 33.7 cm3/mol |
| Discovered: Strontium was recognized as distinct from barium in 1790 by Adair Crawford in a mineral sample from a mine near Strontian, Scotland. The element took its name from the Scottish town. The metal was first isolated by Sir Humphry Davy in 1808, by electrolysis. | |
States
| State (s, l, g): solid | |
| Melting point: 1050 K (777 oC) | Boiling point: 1653 K (1380 oC) |
Energies
| Specific heat capacity: 0.30 J g-1 K-1 | Heat of atomization: 164 kJ mol-1 |
| Heat of fusion: 8.30 kJ mol-1 | Heat of vaporization : 144.0 kJ mol-1 |
| 1st ionization energy: 549.5 kJ mol-1 | 2nd ionization energy: 1064.2 kJ mol-1 |
| 3rd ionization energy: 4138 kJ mol-1 | Electron affinity: 5 kJ mol-1 |
Oxidation & Electrons
| Shells: 2,8,18,8,2 | Electron configuration: [Kr] 5s2 |
| Minimum oxidation number: 0 | Maximum oxidation number: 2 |
| Min. common oxidation no.: 0 | Max. common oxidation no.: 2 |
| Electronegativity (Pauling Scale): 0.95 | Polarizability volume: 27.6 Å3 |
Appearance & Characteristics
| Structure: ccp: cubic close-packed | Color: silvery |
| Hardness: 1.5 mohs | |
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Harmful effects: Strontium's non-radioactive isotopes are considered non-toxic. As a result of its chemical similarity to its fellow Group 2 element, calcium, strontium replaces and mimics calcium in the human body. Absorption of the radioactive isotope 90Sr, distributed due to fallout from nuclear tests, can lead to various bone disorders and diseases. Characteristics: Strontium is a soft, silvery metal. When cut it quickly turns a yellowish color due to the formation of strontium oxide (strontia, SrO) . Finely powdered strontium metal is sufficiently reactive to ignite spontaneously in air. It reacts with water quickly (but not violently like the Group 1 metals) to produce strontium hydroxide and hydrogen gas. Strontium and its compounds burn with a crimson flame and are used in fireworks. Uses: Strontium is used for producing glass (cathode ray tubes) for color televisions. It is also used in producing ferrite ceramic magnets and in refining zinc. The world's most accurate atomic clock, accurate to one second in 200 million years, has been developed using strontium atoms. Strontium salts are used in flares and fireworks for a crimson color. Strontium chloride is used in toothpaste for sensitive teeth. Strontium oxide is used to improve the quality of pottery glazes. The isotope 90Sr is one of the best long-lived, high-energy beta emitters known. It is used in cancer therapy. |
Reactions
| Reaction with air: vigorous, ⇒ SrO, Sr2N3 | Reaction with 6 M HCl: vigorous, ⇒ H2, SrCl2 |
| Reaction with 15 M HNO3: vigorous, ⇒ H2, Sr(NO3)2 | Reaction with 6 M NaOH: vigorous, ⇒ none |
Compounds
| Oxide(s): SrO, SrO2 (strontium peroxide) | Chloride(s): SrCl2 |
| Hydride(s): SrH2 |
Radius
| Atomic radius: 215 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion): 132 pm | Ionic radius (3+ ion): pm |
| Ionic radius (2- ion): pm | Ionic radius (1- ion): pm |
Conductivity
| Thermal conductivity: 35.4 W m-1 K-1 | Electrical conductivity: 5 x 10-6 S m-1 |
Abundance & Isotopes
| Abundance earth's crust: 370 parts per million by weight, 87 parts per million by moles | |
| Abundance solar system: 50 parts per billion by weight, 0.7 parts per billion by moles | |
| Cost, pure: $100 per 100g | |
| Cost, bulk: $ per 100g | |
| Source: Strontium is never found free in nature. The principal strontium ores are celestine (strontium sulfate, SrSO4) and strontianite (strontium carbonate, SrCO3). The main commercial process for strontium metal production is reduction of strontium oxide with aluminum. | |
| Isotopes: Strontium has 28 isotopes whose half-lives are known, with mass numbers 75 to 102. Of these, four are stable: 84Sr, 86Sr, 87Sr and 88Sr. 88Sr is the most abundant in nature at 82.6%. | |
