Radium

**Radium** is a chemical element. The symbol for radium is **Ra**, and its atomic number is 88. It was discovered by Marie Curie and Pierre Curie in the form of radium chloride in 1898. It is a slivery-white alkaline earth metal, but it turns black quickly when it is exposed to nitrogen in the air. All isotopes of radium are radioactive. The radioactivity of radium causes it to glow in the dark.

Radium is used in many things, such as glowing watches, which are now banned because they can cause radiation poisoning. Some of the things radium was used for are now made using less dangerous radioactive elements, such as promethium. It can be used in treating cancer.

In nature, radium is found in tiny amounts in uranium and thorium ores. It does not exist naturally inside of people or other living things; it is dangerous when taken in because it takes the same place as calcium.

## History 
Radium was discovered by Marie Curie and her husband Pierre Curie on 21 December 1898. They found that some radioactive minerals had unknown compounds left over after removing uranium and barium. The unknown compounds were polonium and radium; the discovery was announced to the French Academy of Sciences on 26 December 1898.

The original unit of measurement for radioactivity was called the curie. The unit was equal to the radioactivity of one gram of radium-226, but later it was changed to 3.7×1010 disintegrations per second.

## Properties 
Radium is the heaviest alkaline earth metal and the only radioactive element in the group. It has a silvery-white color, but turns black when it is exposed to air. It is more similar to barium than it is to any other element. It is also similar to barium in the ways it reacts with other things. 

Radium has 33 isotopes. All of these isotopes are radioactive. The isotope which lasts the longest is radium-226: it has a half-life of 1,600 years.

## Uses 
Radium used to be used in glowing paints for watches and other instruments that are used in the dark. Radium stopped being used in the mid-1920s after a lawsuit by five people who were called "Radium Girls". The Radium Girls were told to lick the brushes used to paint with radium, which caused them to ingest the radium. This was very dangerous to their health. Ingesting radium in paint caused sores, anemia, and bone cancer in the Radium Girls. Since it was radioactive, it let out things that shouldn't have been in their bones. The lawsuit caused the dangers of radioactivity to be known by many more people. After the 1960s, radium paint was replaced by less dangerous radioactive paint made from promethium-147 or tritium. The companies tried to lie about this and avoid punishment by saying it was just syphilis.

Radium was also used in different things such as toothpaste and food. Lots of people thought those radioactive things were good for health. These products were made illegal after people found out about the dangers of radioactivity.

Radium is not used now in anything except for nuclear reactors. There are safer elements that can be used in all of the same ways radium was used. Tritium is radioactive, but it's safer than radium because the beta radiation can't get through your skin.

## Toxicity 
Radium is the most toxic radioactive element. It collects in bones when ingested, which causes cancer.  However, even just being around radium can cause cancer. Radium creates radon when it decays. This is even more dangerous, because radon is a gas.

Marie Curie's death was most likely caused by radium. 

## References