Element with Symbol Sr Explained: Atomic Number, Properties, and Uses
By Maya Lin-Takahashi
Naturally occurring strontium consists of four stable isotopes. The most abundant, strontium-88, makes up roughly 82.58% of all natural deposits, followed by strontium-86 at 9.86%, strontium-87 at 7.00%, and strontium-84 at 0.56%. Strontium-87 provides geologists with an accurate isotopic clock: it forms continuously via the beta decay of rubidium-87, allowing researchers to track bedrock ages and pinpoint ancient human migration patterns by tracing groundwater isotopes trapped in fossilized dental enamel.
| Metric or Isotope | Classification / Value | Role & Significance |
|---|---|---|
| Atomic Number (Z) | 38 | Defines proton count in nucleus; establishes position below Ca and above Ba. |
| Standard Atomic Weight | 87.62 u | Weighted average across four terrestrial stable isotopes (⁸⁴Sr, ⁸⁶Sr, ⁸⁷Sr, ⁸⁸Sr). |
| Density & Melting Point | 2.64 g/cm³ | 777 °C (1050 K) | Relatively light density for a structural metal; boils at 1382 °C. |
| Strontium-88 (Stable) | 82.58% abundance | Dominant stable isotope used across industrial salts, ceramics, and optics. |
| Strontium-90 (Synthetic) | Half-life: 28.9 years | Fission byproduct; emits high-energy beta particles; accumulates in bone marrow. |
Maya is a hardware enthusiast who tests and reviews smart home devices, smartphones, wearables, and audio gear. She focuses on practical consumer value and build quality.
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