Which of the following best explains why noble gases do not readily react with other elements?

• A. They have a complete valence electron shell, making them chemically stable.
• B. They have low atomic masses, which prevents chemical reactions.
• C. They have high electronegativity, so they repel other atoms.
• D. They are metals and therefore do not form compounds easily.

Answer: (A)

Verified step by step guidance

1. Understand that chemical reactivity is largely determined by the electron configuration of an element, especially the electrons in the outermost shell, called valence electrons.
2. Recall that noble gases are located in Group 18 of the periodic table and are known for having a full valence electron shell, which means their outermost energy level is completely filled with electrons.
3. Recognize that a complete valence shell makes an atom very stable because it has little tendency to gain, lose, or share electrons, which are the processes involved in chemical reactions.
4. Evaluate the other options: low atomic mass does not prevent reactions, high electronegativity causing repulsion is not accurate for noble gases, and noble gases are nonmetals, not metals, so the statement about metals is incorrect.
5. Conclude that the best explanation for the low reactivity of noble gases is their complete valence electron shell, which makes them chemically stable and unlikely to react with other elements.