Naturally occurring lithium (3Li) is composed of two stable isotopes, lithium-6 (6Li) and lithium-7 (7Li), with the latter being far more abundant on Earth. Radioisotopes are short-lived: the particle-bound ones, 8Li, 9Li, and 11Li, have half-lives of 838.7, 178.2, and 8.75 milliseconds respectively.