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Strontium

Element 38 · Alkaline earth metal

Specimen

Atomic number
38
Atomic mass
87.62
State at room temperature
Solid
Melting point
776.9 °C
Boiling point
1,382 °C
Density
2.64 g/cm³
Discovered
1790

Atomic mass from IUPAC.1 Other physical data from PubChem.2

Can I eat it?

In food and water
Harmful. Food and water contain stable strontium. ATSDR says low levels have not been shown to harm adults. High levels can slow bone growth in children. The US EPA limits strontium in drinking water to 4 mg per liter. 3

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The atom

Sr
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 8
5 (O) outermost 2
Total38

Configuration [Kr] 5s²

5s ↑ ↓
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 38 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Kr core, with one arrow per electron.

Related elements

Group 2
Be Beryllium Mg Magnesium Ca Calcium Ba Barium Ra Radium

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Sources

  1. 1

    IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW), 2024. Abridged Standard Atomic Weights 2024 .

    The atomic mass shown for the 84 elements that have a standard atomic weight.

  2. 2

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  3. 3

    Agency for Toxic Substances and Disease Registry (ATSDR), 2004. ToxFAQs for Strontium .

    • Exposure to low levels of stable strontium has not been shown to affect adult health ... In children, high levels of stable strontium can impair bone growth ... EPA has set a limit of 4000 micrograms strontium per liter of drinking water
  4. 4

    National Institute of Standards and Technology (NIST), 2026. Atomic Weights and Isotopic Compositions for All Elements .

    Isotopic composition of each element; the most abundant isotope sets the neutron count in the nucleus view.