Use the terms in the boxes to fill in the blanks in the following paragraphs. Atoms, Balanced, Chemical Reaction, Coefficients, Correct, Element, Equation, Formula, Mass, Mg, Numbers, Products, Reactants, Substance, Two, Yields

A is a well defined example of a chemical change. A chemical can be used to show the changes that occur in a chemical reaction. In a chemical reaction, the substance on the left side of the arrow are the starting substance. These substances are called . The substances on the right side of the arrow are the substances that result from the reaction. These substances are called . The arrow is read as either produces or . According to the law of conservation of , atoms are neither lost nor gained during a chemical reaction. This law is illustrated when a chemical equation is . When this is done, there will be the same number of of each kind on both sides of the equation. In a chemical equation, the numbers that are placed in front of the symbols and the formulas are called . They are necessary to keep the of atoms in balance. There are several rules for balancing an equation. First, write the correct for each reactant and product. Next, choose the coefficients that make the number of atoms of each on each side of the equation equal. The correctly written formula should not be changed. If you change the formula of a substance, the equation is no longer . Changing a formula will indicate a different than the one intended. To balance the equation Mg + O2 à MgO, first choose coefficients to make the number of atoms of each element on each side of the equation equal. You would need to place a coefficient of