In chemistry, when a chemist refers to the smallest unit of an element that retains the properties of that element, what is being defined?

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

Answer: (D)

Verified step by step guidance

1. Understand the question is asking for the smallest unit of an element that retains the properties of that element.
2. Recall that an isotope refers to atoms of the same element with different numbers of neutrons, so it is not the smallest unit itself but a variant of atoms.
3. Recognize that a molecule is a group of two or more atoms bonded together, so it is larger than a single unit.
4. Know that an ion is an atom or molecule that has gained or lost electrons, giving it a charge, but it still originates from an atom.
5. Conclude that the smallest unit of an element that retains its chemical properties is an atom.