Question

match the term to the definition.
the protons and neutrons in the middle of an atom
when different atoms of an element differ in only the number of neutrons (mass number)
a subatomic particle that can be either a proton or neutron
a specific number of protons and neutrons that make a unique nucleus
nucleus
nuclide
nucleon
isotope

Explanation:

A nucleus is the central part of an atom containing protons and neutrons. A nuclide is a specific combination of protons and neutrons in a nucleus. A nucleon is a subatomic particle that can be a proton or a neutron. Isotopes are different atoms of an element that differ only in the number of neutrons (mass number).

Answer:

A specific number of protons and neutrons that make a unique nucleus - Nuclide
A subatomic particle that can be either a proton or neutron - Nucleon
When different atoms of an element differ in only the number of neutrons (mass number) - Isotope
The protons and neutrons in the middle of an atom - Nucleus