What is the basic unit of an element that retains its properties?

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

Answer: (B)

The basic unit that retains an element’s properties is the atom. An element’s identity comes from its atomic structure—the number of protons defines the element, and the surrounding electrons give it characteristic chemical behavior. The atom is the smallest piece that still behaves like that element; if you break it apart, you lose the element’s identity.

Molecules are made of atoms bonded together and can include different elements; ions are atoms (or molecules) with a net charge, which often changes their properties. So the atom best fits as the unit whose properties define the element.