Neon (10Ne) possesses three stable isotopes, 20Ne, 21Ne, and 22Ne. In addition, 17 radioactive isotopes have been discovered ranging from 15Ne to 34Ne, all short-lived. The longest-lived is 24Ne with a half-life of 3.38 minutes. All others are under a minute, most under a second. The least stable is 15Ne with a half-life of 7.7×10−22 s. See isotopes of carbon for notes about the measurement. Neon (10Ne) possesses three stable isotopes, 20Ne, 21Ne, and 22Ne. In addition, 17 radioactive isotopes have been discovered ranging from 15Ne to 34Ne, all short-lived. The longest-lived is 24Ne with a half-life of 3.38 minutes. All others are under a minute, most under a second. The least stable is 15Ne with a half-life of 7.7×10−22 s. See isotopes of carbon for notes about the measurement.