An isotope is an element with the same atomic number but different mass number. most isotope are unstable, having short half life.
Curium-242 is an isotope produced when Plutonium 239 is bombarded by an alpha particle. This reaction between Plutonium 239 and alpha particle gives curium-242, neutron and a high amount of energy as the products.
Curium oxidizes easily, and it is a dangerous metal which can cause cancer initiation when absorbed by biological materials e.g bones or tissue.
