Calcium vs Strontium
Both are alkaline earth metals, so they share the same broad chemistry.
The differences in plain English
- They sit in the same column, group 2, so they have the same number of outer electrons and react in similar ways; the heavier one, Strontium, is usually the more reactive of the two if they are metals, and the less reactive if they are non-metals.
- Both are solids at room temperature.
- Strontium is denser, about 70 per cent more than Calcium (2.64 against 1.55 g/cm³).
- Calcium melts at 842 °C, Strontium at 777 °C.
- An atom of Strontium is about 2.2 times heavier than an atom of Calcium (87.62 u against 40.08 u).
- Calcium pulls electrons more strongly in a bond (electronegativity 1 against 0.95).
Side by side
| Calcium | Strontium | |
|---|---|---|
| Atomic number | 20 | 38 |
| Symbol | Ca | Sr |
| Family | Alkaline earth metal | Alkaline earth metal |
| Group / period | 2 / 4 | 2 / 5 |
| State at room temperature | Solid | Solid |
| Atomic mass | 40.078 u | 87.621 u |
| Density | 1.55 g/cm³ | 2.64 g/cm³ |
| Melting point | 842 °C | 777 °C |
| Boiling point | 1484 °C | 1377 °C |
| Electronegativity | 1 | 0.95 |
| First ionisation energy | 589.8 kJ/mol | 549.5 kJ/mol |
| Electron configuration | [Ar] 4s2 | [Kr] 5s2 |
| Discovered by | Humphry Davy | William Cruickshank (chemist) |
Calcium
You are carrying about a kilogram of calcium, almost all of it in your bones and teeth. Yet calcium the metal is something few people ever see: a soft, silvery solid that fizzes gently in water and dulls quickly in air. The metal is a curiosity. Its compounds are everywhere, in chalk, limestone, marble, seashells, cement, plaster and indigestion tablets.
- Cement manufacture is one of the largest single industrial sources of carbon dioxide, because heating limestone drives off the gas chemically as well as burning fuel.
- Calcium colours a flame brick red, which is how it shows up in a flame test and in some fireworks.
Strontium
Strontium is the only element named after a place in the United Kingdom. The lead mines at Strontian, a small village on the west coast of the Scottish Highlands, produced an unusual mineral in the 1780s, and the metal inside it was named accordingly. It is a soft, silvery alkaline earth metal that behaves so much like calcium that the human body cannot tell them apart.
- Strontium is the only element named after a place in the United Kingdom: Strontian, a village in the Scottish Highlands.
- A survey of baby teeth in St Louis found strontium-90 from nuclear tests rising year by year, which helped bring about the 1963 Partial Test Ban Treaty.
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More comparisons
Read more about each element
Both belong to the alkaline earth metals. See all element comparisons or browse all 118 elements.
Data from Periodic-Table-JSON (CC BY-SA); temperatures rounded to the nearest degree. Written by Anthony. Published September 2026.