Writing Formulas -criss-cross Method-

Chemistry is often called the "central science," and its language is the chemical formula. Whether you are balancing a combustion reaction, calculating molar mass, or predicting solubility, everything begins with a correct formula. If you write ( CaO ) instead of ( Ca_2O_2 ), you change the substance entirely.

Iron (III) means ( Fe^+3 ). Iron (II) means ( Fe^+2 ). Always use the Roman numeral as the charge. Don't guess. writing formulas -criss-cross method-

This is where students often slip.