Sodium is the 11th element on the periodic table where it is represented by the symbol Na. It is a soft metal, with a silvery-white appearance and it is highly reactive. It is the 6th most abundant element in the crust of the Earth. All of the natural sodium on the planet is made up of 23Na, which is the only stable isotope of sodium. This means that sodium is a monoisotopic element (element with only 1 stable isotope). However, sodium has many other isotopes that have been discovered.
How many isotopes does sodium have?
We already know that sodium only has one stable isotope, which makes up virtually 100% of the sodium on the planet. However, 2 other unstable isotopes are also found in trace amounts. These are 24Na and 22Na and they are known as cosmogenic isotopes because they are created by high energy cosmic rays interacting with the nucleus of an atom. 24Na and 22Na are also the two unstable isotopes of sodium that have the longest half life. 24Na has a half life of 2.605 years and 24Na has a half life of about 15 hours. 17 other radioactive (unstable) isotopes of sodium have also been identified and most of these have a half life of less than a second.
Did you know?
Certain types of radiation exposure converts some of the stable sodium isotope in human blood to 24Na. This can be measured to assess the radiation dosage that the person has been exposed to.