This is what cesium, one of the most reactive metals, looks like

Cesium is considered one of the most reactive metals: it is an element that reacts easily in chemical reactions.

Reactions occur especially with water and oxygen, often generating heat or causing explosions, and therefore require special storage conditions.

In its pure form it is striking with a bright golden luster, like rare gold. In air, cesium oxidizes rapidly, losing its luster and becoming covered with a dull oxide film.

It reacts particularly strongly with water, causing an explosive reaction.

This property makes it very dangerous to work in the laboratory and to store in the air.

Cesium is usually stored under a layer of kerosene and in airtight containers to avoid contact with moisture and air.

Cesium is unique not only in its danger, but also in its accuracy: atomic clocks powered by the cesium-133 isotope count time to the nearest billionth of a second.

These clocks set the global time standard and are used, for example, in GPS and telecommunications.

This metal helps in space: its ions accelerate the ion engines of satellites.