I am the smallest unit of an element. I consist of a nucleus surrounded by electrons. My name comes from the Greek word meaning "indivisible." Who am I?

You are an atom. Atoms are the fundamental building blocks of matter, making up everything around us. The term "atom" is derived from the Greek word "atomos," which means "indivisible," reflecting the ancient belief that atoms were the smallest units of matter and could not be divided further. Each atom consists of a central nucleus made up of protons and neutrons, surrounded by one or more electrons that orbit the nucleus. The arrangement and number of these subatomic particles define the unique properties of each element in the periodic table. Thus, atoms play a crucial role in chemistry, physics, and the understanding of the material world.