A radioactive element or radioactive substance have a half life
Explanation:
The half life of a radioactive element is defined as the time taken for the atoms of the radioactive elements to decay to half the original number
Radioactive decay
Radioactive decay simply the process by which the nucleus of a heavy radioactive element disintegrates and emits alpha or beta particles along with Gama rays
Law of radioactivity
The law states that when a radio active element decays or disintegrates it forms a new element two places below in the periodic table with emission of alpha particles or two places above the element in the periodic table with emission of beta particle.
Self centered means you think about yourself and can sometimes mean that you're arrogant. Self aware means you are aware of certain things you do. Self centered has a negative connotation while self aware has a positive one.
