Neon possesses three stable isotopes: ²⁰ Ne , ²¹ Ne , and ²² Ne . In addition, 17 radioactive isotopes have been discovered, ranging from ¹⁵ Ne to ³⁴ Ne , all short-lived. The longest-lived is ²⁴ Ne with a half-life of 3.38 min. All others are... Wikipedia