The smallest particle of an element is the:

**The reasoning** An **atom** is the smallest particle of an element that still retains the chemical identity of that element. Think of it like this: if you keep dividing a piece of iron into smaller and smaller bits, the tiniest piece you can get that's still iron is *one iron atom*. Go smaller (split the atom into protons, neutrons, electrons), and you no longer have iron — you have subatomic particles. This is the definition that sits at the foundation of chemistry: **Element → made of atoms**. **Why the wrong options tempt you** - **Molecule (A)**: This tricks you because molecules *are* small particles — but they're made of *two or more atoms* bonded together (like O₂ or H₂O). Not all elements exist as molecules naturally. - **Ion (C)**: An ion is just an atom that's gained or lost electrons. It's still an atom, just charged. Not smaller. - **Compound (D)**: A compound contains *different* elements combined (like NaCl). Way bigger than a single atom. **Quick takeaway** "Atom = smallest unit of an *element*; molecule = two or more atoms joined together."