Property by virtue of which metals can be beaten into shapes

The property which allow the metals to be hammered into thin sheets is called malleability. Gold and silver are the best malleable metals. It is due to the property of malleability that metals can be bent to form objects of different shapes by beating with a hammer.

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.