Structure
Not a diagram of dots on rings — a Monte-Carlo sample of the actual probability density |ψ|² for each occupied subshell. Drag to rotate. Blue and violet mark opposite signs of the wavefunction, which is what makes bonding possible.
Measured values
Every bar shows where strontium sits among all 118 elements for that property.
Sources: IUPAC 2021 standard atomic weights · CRC Handbook of Chemistry and Physics · NIST. Values marked ~ are predicted rather than measured.
Size, to scale
Radius 215 pm — that is 0.215 nm, so about 2326 million of them side by side would span a millimetre.
Thermal range
Strontium is liquid over a 605 K window, from 1050 K to 1655 K.
The story
Strontium is the brilliant red flame element that lights up fireworks displays and helps doctors see inside your bones. This soft, silvery alkaline earth metal burns with one of the most intense and beautiful red colors in chemistry, making it absolutely essential for pyrotechnics and signal flares. Named after the Scottish village of Strontian where it was first discovered, strontium has become central for both celebration and medical diagnosis. Discovered in 1790 by Irish scientist Adair Crawford while analyzing a mysterious mineral from lead mines near Strontian, Scotland, strontium was initially confused with barium due to their similar properties. The mineral, later called strontianite, contained a new earth (oxide) that produced different flame colors than any known substance. Pure metallic strontium wasn't isolated until 1808 by Sir Humphry Davy using electrolysis. What makes strontium absolutely spectacular is its pyrotechnic properties. Strontium compounds burn with an incredibly intense, pure red flame that can be seen for miles. This makes strontium nitrate and strontium carbonate essential ingredients in red fireworks, emergency flares, and military signal devices. The red color is so distinctive and bright that it's used in tracer bullets and distress signals. Strontium has revolutionized medical imaging through strontium-90, which is used to treat eye diseases and bone cancer. More importantly, strontium ranelate has been used as a medication to treat osteoporosis, helping strengthen bones and reduce fracture risk. The element's similarity to calcium allows it to be incorporated into bone structure. Here's something both fascinating and concerning: radioactive strontium-90 from nuclear weapons testing and accidents accumulates in bones like calcium, making it one of the most dangerous radioactive contaminants. However, stable strontium is completely safe and even beneficial in small amounts.
William Cruickshank discovered strontium in 1787 while analyzing strontianite mineral from lead mines near Strontian, Scotland. Humphry Davy first isolated pure strontium metal in 1808 through electrolysis, naming it after its discovery location.
Applications
Strontium creates the brilliant red colors that illuminate celebrations worldwide, while its unique properties enable advanced ceramics, medical imaging, and specialized glass applications requiring exceptional performance characteristics.
Strontium carbonate and nitrate produce pure red flames in fireworks, flares, and signal devices. The characteristic 460.7 nm emission line creates the intense red color essential for patriotic displays, emergency signaling, and military applications where color recognition is critical.
Strontium ferrite magnets provide cost-effective permanent magnet solutions for motors, speakers, and magnetic assemblies. Strontium titanate ceramics exhibit high dielectric constants essential for capacitor applications and microwave electronics.
Strontium-89 radiotherapy treats bone cancer pain through targeted radiation delivery to bone tissue, while strontium ranelate pharmaceuticals help prevent osteoporotic fractures by promoting bone formation and reducing bone resorption.
Where it comes from
370 mg/kg of Earth's crust · more abundant than 87% of elements
Strontium occurs naturally in celestite (SrSO₄) and strontianite (SrCO₃) minerals, typically associated with sedimentary deposits and hydrothermal systems. Major deposits occur in Turkey, Spain, and Mexico, with celestite being the primary commercial source.
Handling
Strontium compounds exhibit low toxicity, though radioactive isotopes require special handling. Standard laboratory safety procedures prevent exposure to strontium dusts and solutions.
Dust control measures and basic personal protective equipment provide adequate protection for most strontium applications. Radioactive isotopes require radiation safety protocols and specialized disposal procedures.
Quick answers
Strontium (symbol Sr) is element 38 on the periodic table, a alkaline earth metal in period 5, group 2. The element that paints fireworks crimson and, as strontium-90, once fell out of the sky after weapons tests. At room temperature it is a solid.
[Kr] 5s², giving 5 occupied shells holding 2, 8, 18, 8, 2 electrons respectively.Strontium melts at 1050 K (776.9 °C) and boils at 1655 K (1381.9 °C).
The standard atomic weight of Strontium is 87.62 u. That is a weighted average across its naturally occurring isotopes, which is why it is rarely a whole number.
Strontium has a density of 2.64 g/cm³. Water is 1.0 g/cm³, so a block of strontium is about 2.6× heavier.
Strontium has a Pauling electronegativity of 0.95. The scale runs from 0.70 (francium, the least greedy for electrons) to 3.98 (fluorine, the most). A value this low means it readily gives its outer electrons away, forming positive ions.
Strontium was discovered in 1790 by Adair Crawford. It is named after strontian, a village in Scotland.
Strontium makes up about 370 mg/kg of the Earth's crust — common enough to be mined at scale.