Cadmium

In the early 1800s, doctors in Germany made medicines out of a substance called calamine to help with ailments like swollen joints. But sometimes these medicines, that were supposed to be white, turned yellow! In 1817, Friedrich Stromeyer, a curious doctor, figured out that the color change only happened when the calamine had a certain material in it. He separated out the material and discovered it was a new element! He called it cadmium, after the Greek word for calamine—kadmeia.

However, at around the same time that Stromeyer made his discovery, two other German scientists—K.S.H. Hermann and J.C.H Roloff—also discovered cadmium. Although Stromeyer generally gets the credit for discovering the element, historians aren’t sure who technically discovered cadmium first!

Cadmium metal, which is soft and shiny, looks a lot like silver. Cadmium melts at a low temperature. It’s also ductile, meaning that it can stretch without breaking. Cadmium metal doesn’t corrode easily, which is why the element gets used in electroplating. However, cadmium is poisonous and can cause illnesses like cancer.

Almost all cadmium is used in rechargeable batteries. These batteries can power tools, portable computers, and household appliances, among other things. Because cadmium doesn’t corrode easily, it can be used for electroplating, which involves protecting a metal by coating it with a thin layer of a different metal.

Cadmium can be bought as an oxide, chloride, or sulfide. Cadmium sulfides range in color from yellow to maroon, which is why they’re often used in paints or dyes. Mixing a little cadmium into another metal can help make the metal stronger, or better at conducting electricity, or easier to melt, among other things.

There are eight isotopes of naturally occurring cadmium, two of which are radioactive.

Cadmium can be found in ocean water and in the Earth’s crust, although it’s relatively rare. Most cadmium comes from processing zinc, copper, and lead ores.