Which term or terms can be used to describe the model shown: element, compound, or molecule?

The terms that can be used to describe the model are compound and molecule.

The term compound is used to describe two or more elements that are chemically combined together.

In this case, nitrogen and hydrogen are chemically combined together so the model represents a compound.

Also, the model represents the smallest unit of the substance ammonia. This smallest unit of the substance that retains all the properties of the substance is called a molecule.

Hence, the model represents both a compound and a molecule.

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Ammonia can be described as a compound and a molecule.

Explanation:

A compound consists of two or more different types of atoms bonded together and a molecule consists of two or more atoms bonded together. They can be the same atoms or a combination of different atoms. The model shown fits both of these terms. It is not an element because an element consists of only one type of atom.

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.