Radium

radioactive · glowing · toxic · periodic table

Glowing in the dark. Radium can excite special fluorescent chemicals and make them glow, which is why people used it in paints for watch dials and clock faces that shined in the dark.

Radioactive and rare. All radium atoms are radioactive, meaning they constantly break apart and release energy. The most stable type lasts about 1,600 years before it fully decays.

Silvery-white metal. Pure radium looks shiny and silvery-white, but when it touches air, it quickly reacts with nitrogen and turns black on the surface.

Very toxic. Radium is dangerous because it accumulates in your bones and emits harmful radiation that can cause cancer. Scientists discovered this danger only after it was already widely used.

Group 2 element. Radium is the sixth element in the alkaline earth metals family on the periodic table, which are elements that sit in the same column.