express your answer as a chemical formula express your answer as an integer express your answer as an isotope express your answer as an ion express your answer as a chemical symbol express your answer as a decimal express your answer as a chemical equation express your answer as an inequality express your answer as a nuclear equation express your answer as an integer chemistry fecl2 express your answer as an ion n express your answer as an ion mg express your answer as an ion si3s23p2 express your answer as an integer na express your answer as an ion