2. Describing Chemical Reactions Section 1 Chemical Change A chemical change is the process by which one or more substances change into one or more new substances whose chemical and physical properties differ from those of the original substances. Evidence of a Chemical Reaction

3. Constructing a Chemical Equation A correctly written chemical equation shows the chemical formulas and relative amounts of all reactants and products. NaHCO 3( s ) + HC 2 H 3 O 2( aq ) → NaC 2 H 3 O 2( aq ) + CO 2( g ) + H 2 O ( l ) Reactants- The names of the substance that are chemically going to change into new substances. Found on the left side of a chemical equation. Products- The names of the substances that are chemically formed from the reactants. Found on the right side of a chemical equation. Phase symbols- State the phase of the substance when the chemical reaction occurs. Reactants Products Phase

4. Common Symbols used in equations

5. Word equations Word equations state a chemical equations in sentences. Solid silicon and solid magnesium chloride form when silicon tetrachloride gas reacts with magnesium metal. Write a word equation and an unbalanced formula equation. Include all of the appropriate notations. Change the word equation below into a chemical equation.