ElementsWhat are the alkaline earth metals?
The alkaline earth metals fill the second column. They are harder and less reactive than the alkali metals next to them, but still too reactive to be found pure in nature. Each atom has two outer electrons. Their compounds are common in rocks: limestone, chalk and marble are calcium carbonate. Calcium and magnesium are needed by all living things. Several of them give strong colours to flames, which is why they are used in fireworks.
The family in numbers
Melting points in this family run from 649.9 °C (magnesium) to 1,287 °C (beryllium). Among its solid members, the least dense is calcium (1.54 g/cm³) and the densest is radium (5 g/cm³). The most recently discovered member is radium (1898).
All alkaline earth metals compared
| No. | Symbol | Name | Atomic mass | State | Melts at | Boils at | Density g/cm³ | Discovered |
|---|---|---|---|---|---|---|---|---|
| 4 | Be | Beryllium | 9.012183 | Solid | 1,287 °C | 2,471 °C | 1.85 | 1798 |
| 12 | Mg | Magnesium | 24.305 | Solid | 649.9 °C | 1,090 °C | 1.74 | 1808 |
| 20 | Ca | Calcium | 40.08 | Solid | 841.9 °C | 1,484 °C | 1.54 | 1808 |
| 38 | Sr | Strontium | 87.62 | Solid | 776.9 °C | 1,382 °C | 2.64 | 1790 |
| 56 | Ba | Barium | 137.33 | Solid | 726.9 °C | 1,897 °C | 3.62 | 1808 |
| 88 | Ra | Radium | 226.02541 | Solid | 699.9 °C | 1,140 °C | 5 | 1898 |
Other families: alkali metals, transition metals, post-transition metals, metalloids, nonmetals, halogens, noble gases, lanthanides, actinides.