In chemistry, the smallest parts of elements that possess the characteristics of those elements are called what?

The correct answer is atoms, which are the fundamental building blocks of matter and represent the smallest units of an element that retain all the chemical properties of that element. Each atom is made up of protons, neutrons, and electrons, with the specific arrangement and type of these particles defining the element itself.

When we consider the characteristics of elements—such as their reactivity, state of matter, and ability to form compounds—those traits are inherently linked to their atomic structure. For example, the way atoms bond with one another to form molecules is directly related to the number and configuration of electrons in their outer shells.

The other options represent different concepts within chemistry. Molecules are comprised of two or more atoms bonded together, thereby representing a larger structure that may not possess the specific characteristics of the individual elements alone. Ions are charged particles that form when atoms gain or lose electrons, altering their chemical properties. Radicals refer to species that contain unpaired electrons, making them highly reactive, but they are not the most basic units of elements. Thus, the essential unit that retains all the properties of an element is the atom.