The structure once believed to be indivisible, consisting of electrons orbiting a nucleus, is called the:

The structure once believed to be indivisible, consisting of electrons orbiting a nucleus, is called the:

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

Answer: (B)

Atoms are the basic units of matter, and they were once thought to be indivisible. The classic picture shows electrons orbiting a central nucleus, which is the model people first used to describe how atoms look and behave. The name atom comes from a word meaning indivisible, and that historical idea helped shape our understanding, even though we now know atoms can be broken down further into smaller particles. This matches the concept tested here and is why it’s the best term. A molecule, by contrast, is formed when two or more atoms bond together. An ion is an atom or molecule that has gained or lost electrons and carries a net charge. A compound is a substance made from two or more elements chemically bonded in a fixed ratio.

Atoms are the basic units of matter, and they were once thought to be indivisible. The classic picture shows electrons orbiting a central nucleus, which is the model people first used to describe how atoms look and behave. The name atom comes from a word meaning indivisible, and that historical idea helped shape our understanding, even though we now know atoms can be broken down further into smaller particles. This matches the concept tested here and is why it’s the best term.

A molecule, by contrast, is formed when two or more atoms bond together. An ion is an atom or molecule that has gained or lost electrons and carries a net charge. A compound is a substance made from two or more elements chemically bonded in a fixed ratio.