Final answer:
The smallest particle of an element that retains the characteristics of the element is an atom, which is incredibly small and determines the identity of the element through the number of protons in its nucleus.
Step-by-step explanation:
The smallest particle of an element that retains the characteristics of the element is an atom. An atom is the smallest unit of ordinary matter that embodies the properties of a chemical element. Atoms are incredibly tiny, typically around 100 picometers in size.
The number of protons in the atom's nucleus determines which element it is. For example, all atoms of gold contain the same number of protons. If an atom were split into smaller parts, it would no longer maintain the properties specific to that element. Atoms join together to form molecules, which are the building blocks of all matter.