What is the smallest portion of an element that exhibits all chemical properties?

• A. Atom
• B. Molecule
• C. Compound
• D. Ion

Answer: (A)

Chemical properties come from the electrons surrounding an atom, so the smallest piece that still shows all the element’s chemical behavior is the atom itself. Atoms define the identity of an element, and breaking an atom would remove its characteristic electronic structure. A molecule is a group of atoms bonded together and can exist for elements in diatomic form, but it’s not the smallest unit that carries the element’s identity. A compound combines different elements, so it isn’t the single-element unit either. An ion is a charged version of an atom with altered electron count, which changes its chemical properties. So the neutral atom is the smallest portion that retains all the chemical properties of the element.