Which of the following is the smallest possible piece of a pure substance that retains its chemical properties?

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

Answer: (C)

Verified step by step guidance

1. Understand the question: It asks for the smallest possible piece of a pure substance that still retains its chemical properties.
2. Recall definitions: An electron is a subatomic particle with a negative charge but does not retain chemical properties on its own.
3. Consider an ion: An ion is an atom or molecule with a net electric charge, but it may not represent the smallest unit retaining chemical properties because it can be a charged atom or group of atoms.
4. Consider a molecule: A molecule is a group of atoms bonded together, representing the smallest unit of a compound that retains chemical properties, but molecules are made of atoms.
5. Consider an atom: An atom is the smallest unit of an element that retains the chemical properties of that element, making it the correct answer.