What is the smallest particle that still retains the characteristics of an element?

• A. Proton
• B. Molecule
• C. Atom
• D. Nucleus

Answer: (C)

The main idea is that an element is defined by its atoms, and the atom is the smallest unit that still behaves as that element in chemistry. An atom contains a nucleus of protons and neutrons and surrounding electrons, and it’s the arrangement of those electrons that gives the element its characteristic reactions and properties. A single proton isn’t an element by itself, and the nucleus is only part of the atom. A molecule is built from two or more atoms and is bigger; even for elements that exist as diatomic molecules (like O2), you’re looking at more than one atom bonded together. So the atom is the smallest piece that retains the element’s chemical identity.