A student sketches an atom showing several electron shells around a nucleus. The student labels the shell closest to the nucleus as having the lowest energy. Why do electrons in this inner shell have lower energy than electrons in shells farther away?

• A. Inner-shell electrons move more slowly and therefore lose all chemical activity
• B. Inner-shell electrons contain less electric charge than outer-shell electrons
• C. Inner-shell electrons are strongly attracted to the positively charged nucleus
• D. Inner-shell electrons are responsible for forming all chemical bonds between atoms

Answer: (C)