Silicon is a chemical element with the atomic number 14 and represented by the chemical symbol Si. It is a nonmetal element and is similar to the elements carbon and boron. Silicon is extremely common on Earth (it is the 2nd most common in the crust of the Earth) and in the universe (6th most common element by mass). It is very rarely found in free form and is usually found as a part of minerals with other elements. All naturally occurring is made up of one of three stable isotopes. However, a number of other isotopes of silicon have also been found. Let’s find out how many have been identified.
How many isotopes does silicon have?
The three stable isotopes of silicon are 28Si, 29Si and 30Si. About 92.23% of all silicon on Earth is made up of 28Si, 4.67% is made up of 29Si and 3.1% is made up of 30Si.
There are also 21 known unstable (radioactive or radioisotope) isotopes of silicon. 32Si is the most stable of any of these radioisotopes and is estimated to have a half life of about 170 years. The second longest half life belongs to 31Si at just 157.3 minutes. The remaining unstable isotopes all have have-lives of under 7 seconds and most are less than one tenth of a second.
The six unstable isotopes with mass numbers less than 28 mostly decay to aluminum isotopes and the 16 unstable isotopes with mass numbers above 28 mostly decay to phosphorus isotopes.
Did you know?
32Si is produced by cosmic ray spallation and trace amounts of this isotope can be found naturally!