Which of the following best describes the role of electrons within an atom?

• A. Electrons bind protons and neutrons together in the nucleus.
• B. Electrons are responsible for the mass of the atom.
• C. Electrons determine the chemical properties and reactivity of the atom by occupying energy levels around the nucleus.
• D. Electrons are found in the nucleus and contribute to the atomic number.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the structure of an atom, which consists of a nucleus containing protons and neutrons, and electrons that occupy regions called energy levels or orbitals around the nucleus.
2. Step 2: Recognize that protons have a positive charge, neutrons have no charge, and electrons have a negative charge, and that the nucleus contains almost all the mass of the atom due to protons and neutrons.
3. Step 3: Know that electrons do not reside in the nucleus but move around it in defined energy levels, and their arrangement in these levels determines how an atom interacts chemically with other atoms.
4. Step 4: Understand that electrons are responsible for chemical properties and reactivity because they can be gained, lost, or shared during chemical reactions, forming bonds between atoms.
5. Step 5: Conclude that the correct description of electrons' role is that they determine the chemical properties and reactivity of the atom by occupying energy levels around the nucleus.