Potassium is a highly reactive metal that is silvery-gray in appearance. It is a chemical element with the atomic number 19 and is represented by the chemical symbol K. It was discovered and first isolated by Humphry Davy in 1807. Potassium is formed by the nucleosynthesis of lighter atoms, which mostly occurs in Type II supernovas. Potassium doesn’t occur in its free form on Earth because it is highly reactive, but it is commonly found in minerals. In fact, it is the 17th most common element on the planet and 20th most common in the solar system. All naturally occurring potassium consists of three isotopes, but many others have been identified.
How many isotopes does potassium have?
The three naturally occurring isotopes of potassium are 39K, 40K and 41K. 39K makes up about 93.3% of all naturally occurring potassium, 41K makes up about 6.7% and the remaining tiny fraction is 40K. 39K and 41K are stable isotopes, but 41K is actually a radioactive isotope. It does have a very long half life and eventually decays to 40Ar and 40Ca.
There are also 22 other isotopes of potassium that have been identified. All of these isotopes are unstable and have half lives of less than a day. Most of these isotopes have half lives of less than a second. The most unstable potassium isotopes are 33K and 34K, which have half lives of less than 25 nanoseconds!
Did you know?
40K is a very important isotope. It can be used to date rocks and as a tracer in the study of weathering. It is also used in school studies as a radioactive source. It is also found in plants, animals and humans and is the largest natural source of radioactivity in the human body.
Foods high in potassium, such as bananas, contain this naturally occurring radioactive potassium (yes bananas are radioactive!). A truck load of bananas can actually create a false alarm when scanned by a Radiation Portal Monitor. Despite this, foods containing potassium are perfectly safe and there is no need to be alarmed!