Which term describes an atom that includes a nucleus and electrons?

• A. Nuclide
• B. Isotope
• C. Atomic Number
• D. Atom

Answer: (D)

An atom is the term for the basic unit of matter that includes a central nucleus and surrounding electrons. The nucleus contains protons and neutrons, while the electrons form the electron cloud around it. A nuclide describes only a nucleus with a specific number of protons and neutrons, not the electrons. An isotope is a version of an element that has the same number of protons but a different number of neutrons, focusing on nuclear composition. The atomic number is the count of protons, which identifies the element, but by itself it doesn’t describe the whole atom with its electrons. So, the term that describes an atom containing both the nucleus and the electrons is the atom.