Which of the following best describes valence electrons and explains their significance in chemistry?

• A. Valence electrons are protons located in the nucleus; they determine the atomic number.
• B. Valence electrons are the electrons in the outermost shell of an atom; they determine the atom's chemical reactivity and ability to form bonds.
• C. Valence electrons are neutrons in the outer shell; they are important for the atom's stability.
• D. Valence electrons are the electrons found in the innermost shell of an atom; they are responsible for the atom's mass.

Answer: (B)

Verified step by step guidance

1. Understand that valence electrons are specifically the electrons located in the outermost electron shell (energy level) of an atom.
2. Recognize that these valence electrons are crucial because they participate in chemical bonding and reactions, determining how an atom interacts with other atoms.
3. Recall that protons are positively charged particles found in the nucleus and define the atomic number, but they are not valence electrons.
4. Note that neutrons are neutral particles in the nucleus and do not influence chemical reactivity directly, so they are not valence electrons.
5. Remember that electrons in the innermost shells are core electrons and do not typically participate in bonding or chemical reactions, unlike valence electrons.