Which of the following is true about an atom?

An atom is indeed the smallest particle of an element that retains its chemical properties, which is why this statement is accurate. Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons that occupy specific energy levels or orbitals. This unique structure is what allows each atom to define the properties of the element it represents. For instance, a carbon atom has unique properties that distinguish it from other elements like oxygen or hydrogen.

Atoms combine to form molecules, but as individual entities, they maintain the distinct characteristics of the element. Therefore, while larger structures and compounds may be formed from atoms, the atom itself is the fundamental building block that preserves the properties unique to that element. This understanding is crucial in chemistry and explains the behavior of matter at a basic level.