Isotopes of copper

Copper (₂₉Cu) has two stable isotopes, ⁶³Cu and ⁶⁵Cu, along with 28 known radioisotopes from ⁵⁵Cu to ⁸⁴Cu. The most stable radioisotope, ⁶⁷Cu, has a half-life of only 61.83 hours, then follow ⁶⁴Cu at 12.70 hours and ⁶¹Cu at 3.34 hours. The others have half-lives all under an hour and most under a minute. The isotopes with mass below 63 generally undergo positron emission and electron capture to nickel isotopes, while isotopes with mass above 65 generally undergo β⁻ decay to zinc isotopes. The single example in between, ⁶⁴Cu, decays both ways.

There are at least 10 metastable isomers of copper, of which the most stable is ^68mCu with a half-life of 3.75 minutes.