What is the smallest particle of an element?

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

Answer: (B)

The smallest particle of an element is the atom because it is the basic unit that retains the chemical properties of that element. Atoms are the building blocks from which elements are made, and they can combine with other atoms to form molecules, which is why a molecule isn’t the smallest unit of an element—it’s just a group of atoms bonded together. An ion is a charged form of an atom (or molecule) that has gained or lost electrons, so it’s a different state of the same basic unit, not the fundamental unit itself. An electron is a subatomic particle, much smaller than an atom, and while essential to the atom’s structure, it does not define the element on its own. So the atom is the best answer.