The breaking apart of the nucleus of an atom is referred to as __ nuclear fission nuclear fusion physical change chemical reaction

## Step 1<br />The problem is asking for the term that describes the process of the nucleus of an atom breaking apart. This process is known as nuclear fission.<br /><br />## Step 2<br />Nuclear fission is a type of nuclear reaction where the nucleus of an atom splits into two or more smaller nuclei, along with the release of a large amount of energy. This is the process that is used in nuclear power plants and atomic bombs.<br /><br />## Step 3<br />On the other hand, nuclear fusion is a process where two or more atomic nuclei come together to form a larger nucleus. This is the process that powers the sun and other stars.<br /><br />## Step 4<br />A physical change is a type of change in which the form of matter is altered but one substance is not transformed into another. This is not the process being described in the problem.<br /><br />## Step 5<br />A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. This is not the process being described in the problem.