1.  Chemical changes occur during chemical reactions.  Atoms rearrange and one substance changes into another substance.  Reactant = substance used in the reaction  Product = substance made by the reaction Yttrium hydride (Y–H) cluster reacts with a rhodium–carbon monoxide (Rh–CO) complex to make a new organic–multimetallic species.

2.  Start with reactants  Arrows in the middle – reads as “makes”  Ends with products

3.  Magnesium - silvery metal, used in fireworks  At high temperatures it reacts with oxygen and burns  Creates bright, white glow  Magnesium + Oxygen → Magnesium Oxide (metal) (gas) (white powder)

4.  During a chemical reaction 1. No matter can be created 2. No matter can be destroyed…only changed Matter is always “conserved”! Total mass of reactants = total mass of products Example = Making a cake Mass of ingredients = mass of finished cake (plus water vapor, carbon dioxide)

5.  When atoms or molecules interact, it can result in three different kind of reactions. 1. Decomposition → 2. Combination + → 3. Replacement + →

6.  Compounds split apart to form smaller compounds and elements  Model = Truck is unhitched from trailer  Example = Electricity in water cause hydrogen and helium to break apart

7.  Elements or compounds come together to make new compounds  Model = truck being connected to a trailer  Example = Iron and sulfide combine to make iron sulfide (see p. 56)

8.  Two or more compounds split apart and switch places to make new compounds  Model = 2 trucks can switch trailers  Example = a burning candle  Candles have carbon and hydrogen atoms  Breaks apart to make new compound of carbon dioxide and water