Strontium Element Properties
Complete reference for Strontium (Sr, element 38): atomic data, electron configuration, isotopes, physical constants, and unit converter.
Strontium
Alkaline Earth Metal — Period 5, Group 2
Atomic Identity
Periodic Table Locator — Period 5 Neighborhood (s-block)
Strontium (Z=38) sits between rubidium (alkali metal) and yttrium (transition metal) in Period 5. It is directly below calcium (Z=20) and above barium (Z=56) in Group 2.
Electron Configuration
No unpaired electrons — all orbitals filled
Key Isotopes of Strontium
| Isotope | Symbol | Protons | Neutrons | Mass (u) | Natural Abundance | Stability |
|---|---|---|---|---|---|---|
| Strontium-84 | ⁸⁴Sr | 38 | 46 | 83.913419 | 0.56% | Stable |
| Strontium-86 | ⁸⁶Sr | 38 | 48 | 85.909261 | 9.86% | Stable |
| Strontium-87 | ⁸⁷Sr | 38 | 49 | 86.908878 | 7.00% | Stable |
| Strontium-88 | ⁸⁸Sr | 38 | 50 | 87.905613 | 82.58% | Stable |
| Strontium-89 | ⁸⁹Sr | 38 | 51 | 88.907451 | Radioactive |
Unstable
β⁻ decay, t½ = 50.5 d |
| Strontium-90 | ⁹⁰Sr | 38 | 52 | 89.907738 | Radioactive |
Unstable
β⁻ decay, t½ = 28.8 yr |
| Strontium-82 | ⁸²Sr | 38 | 44 | 81.918402 | Radioactive |
Unstable
EC + β⁺, t½ = 25.4 d |
| Strontium-85 | ⁸⁵Sr | 38 | 47 | 84.912933 | Radioactive |
Unstable
Electron capture, t½ = 64.8 d |
Strontium-88 accounts for ~83% of natural strontium. Sr-87 is partially radiogenic (from ⁸⁷Rb decay) and its ratio to Sr-86 is a cornerstone geochronometer. Sr-90 is the most hazardous fission product, mimicking calcium in bone. Sr-89 is used medically to palliate bone pain from metastatic cancer.
Physical Properties
Chemical Properties
Ground State Quantum Numbers
Notable Emission Lines
Strontium produces a characteristic crimson-red flame in a flame test, distinct from the brick-red of calcium. The resonance line at 460.73 nm is used in atomic absorption spectroscopy (AAS) for strontium analysis in water and biological samples.
Property Unit Converter
Convert common Strontium property values between units. Enter a value and select the conversion.
Common Strontium Compounds
| Compound | Formula | Common Name | Key Uses |
|---|---|---|---|
| Strontium carbonate | SrCO₃ | Strontianite | CRT glass faceplate (shielding), ferrite magnets, red fireworks, ceramic capacitors |
| Strontium sulfate | SrSO₄ | Celestite (celestine) | Primary ore mineral; source of all commercial strontium; drilling fluids |
| Strontium oxide | SrO | Strontia | CRT glass, stabilizer in TV picture tubes, catalyst support |
| Strontium hydroxide | Sr(OH)₂ | Strontium hydroxide | Sugar refining (strontium saccharate process), lubricating greases |
| Strontium nitrate | Sr(NO₃)₂ | Strontium nitrate | Red signal flares, fireworks oxidizer, tracer ammunition |
| Strontium chloride | SrCl₂ | Strontium chloride | Desensitizing toothpaste (sensitive teeth), aquaculture, gamma-ray source (Sr-90/Y-90) |
| Strontium titanate | SrTiO₃ | Tausonite | High-k dielectric in capacitors, substrate for thin-film deposition, gemstone simulant |
| Strontium ranelate | C₁₂H₆N₂O₈SSr₂ | Protelos/Osseor | Pharmaceutical for osteoporosis (EU, now restricted); dual mechanism on bone remodeling |
Key Facts About Strontium
Crimson Flame and Fireworks
Strontium salts produce a deep crimson-red flame due to intense emission lines near 606 nm and 670 nm. This property is exploited in red signal flares, road safety flares, fireworks, and tracer rounds. Strontium carbonate and strontium nitrate are the two most common pyrotechnic reagents for producing red color.
Sr-87/Sr-86 Geochronometer
The ⁸⁷Sr/⁸⁶Sr isotope ratio is a fundamental tool in geochemistry, geology, and archaeology. Because ⁸⁷Sr grows from ⁸⁷Rb decay (t½ = 49.9 Ga), measuring this ratio in rocks, minerals, and fossils dates geological events and traces the geographic provenance of water, food, and human remains.
Sr-90 — A Nuclear Fission Hazard
Strontium-90 (t½ = 28.8 yr) is one of the most hazardous nuclear fission products. Its ionic radius is almost identical to Ca²⁺ (118 pm vs. 100 pm), so the body incorporates it into bone mineral in place of calcium. Trapped in bone marrow, Sr-90 and its daughter yttrium-90 emit energetic beta radiation for decades, raising leukemia and bone cancer risk.
Celestite — Primary Ore Mineral
Nearly all commercial strontium is derived from celestite (SrSO₄), a pale blue-white mineral found in evaporite and sedimentary deposits. Major producers include China, Spain, Mexico, and Iran. Celestite is converted to strontium carbonate by reduction with carbon, then processed into other strontium compounds for industrial and specialty uses.
Named After a Scottish Village
Strontium takes its name from Strontian, a village in the Scottish Highlands where the mineral strontianite (SrCO₃) was first identified in 1787 by Adair Crawford and William Cruickshank. The element was isolated in 1808 by Humphry Davy via electrolysis — the same year he also isolated calcium, barium, and magnesium.
CRT Television Shielding
Strontium carbonate was a critical component in the glass faceplates of cathode-ray tube (CRT) televisions and monitors, where it absorbed X-rays emitted by the electron gun, protecting viewers. Up to 35% of the glass by weight was SrCO₃. The decline of CRT technology from the early 2000s onward dramatically reduced global strontium carbonate demand.
Summary
Complete reference for Strontium (Sr, element 38): atomic data, electron configuration, isotopes, physical constants, and unit converter.
How it works
- Browse the atomic identity section for symbol, atomic number, and standard atomic weight.
- Check the electron configuration panel for orbital notation and quantum numbers.
- Review the isotopes table for stable and notable radioactive isotopes with natural abundances.
- Consult the physical and chemical properties panels for melting point, density, ionization energies, and more.
- Use the interactive unit converter to convert strontium property values between common units.
- Explore the mini periodic table locator to visualize where strontium sits among neighboring elements.
Use cases
- Look up strontium constants for chemistry homework or exams.
- Verify atomic data when writing lab reports or research papers.
- Reference isotope data for nuclear chemistry or geochronology (strontium-87/86 ratio) research.
- Convert melting and boiling points between Celsius, Fahrenheit, and Kelvin.
- Teach or learn alkaline earth metal properties using strontium as an example.
- Confirm electron configuration before writing molecular orbital or Lewis dot diagrams.
- Research strontium compounds for pharmaceutical, pyrotechnic, or materials science work.
- Quick-reference ionization energies for electrochemistry or spectroscopy calculations.