Which are different forms of an element that have different numbers of neutrons? ions isolopes compounds moleoules

## Step 1<br />The question is asking for the term that describes different forms of an element that have different numbers of neutrons. This is a concept in chemistry known as isotopes.<br /><br />## Step 2<br />Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This means that while they have the same atomic number (which defines the element), they have different atomic masses.<br /><br />## Step 3<br />The other options provided, ions, compounds, and molecules, do not fit the description given in the question. Ions are atoms or molecules that have gained or lost one or more electrons, giving them a net positive or negative charge. Compounds are substances formed when two or more elements are chemically bonded together. Molecules are the smallest unit of a compound that retains the properties of that compound.