Which subatomic particle is primarily responsible for determining an element's chemical properties?

• A. Proton
• B. Neutron
• C. Quark
• D. Electron

Answer: (D)

Verified step by step guidance

1. Understand that an element's chemical properties are mainly determined by how it interacts with other atoms, which depends on the arrangement and behavior of its electrons.
2. Recall that protons define the identity of an element (its atomic number), but do not directly control chemical behavior.
3. Recognize that neutrons contribute to atomic mass and stability but have little effect on chemical properties.
4. Know that quarks are fundamental particles inside protons and neutrons and do not influence chemical properties at the atomic level.
5. Conclude that electrons, especially those in the outermost shell (valence electrons), are primarily responsible for an element's chemical properties because they participate in chemical bonding and reactions.