Radium is radioactive and occurs in natural decay chains.
Uses and research
Its former uses do not make it an ordinary household material.
A metal and the substances containing it
The alkaline earth metals are in group 2. A pure metal and a compound containing that element can have very different properties. Being present in a rock or material is different from being present as a lump of metal. Elements in the same group have similarities, but their reactions and applications are not identical.
What the atomic number tells us
Radium has atomic number 88. This is the number of protons in its nucleus. A neutral atom also has 88 electrons. Losing or gaining electrons makes an ion; it does not change the element unless the proton count changes.
The model's rings help count electrons by shell. They are not actual circular paths. A model of one atom and the properties of a whole material are different levels of description.
Temperature and state
25°C: Solid
Illustrative particle motion: sizes, distances and speeds are not to scale. Particles represent atoms or molecules.
← CoolHeat →
Melting point 699.85°C / Boiling point 1,139.85°C
Pure element at 1 atmosphere. Image conditions are explained in captions. Pictures do not change with temperature.