1. Describing chemical reactions Page 23 of INB

2. Essential Question: What are the signs that a different substance has been formed by a reaction?

3. Chemical reactions Chemical reactions: the process by which one or more substances are changed into one or more DIFFERENT substances. Indications of a reaction: 1)Energy (heat or light) is produced 2)Produces a gas 3)Formation of a precipitate 4)Color Change.

4. Chemical Equations: Characteristics: 1)Summarizes the chemical change 2)Must contain the correct chemical formulas for the reactants and products. 3)Law of conservation of mass must be followed. - The same # of atoms of each element must appear on each side of the equation.

5. Writing Chemical Formulas Write the word formula first, then convert to symbols. Sodium oxide is placed in an aqueous solution and produces sodium hydroxide.