Two important principles to remember from last lesson… Every chemical compound has a ___________ which can not be altered. You can only change the _____________________ A chemical reaction must account for ___________________________that is used because in a chemical reaction __________________ _____________________________________________.

Steps to Word Equations Balancing word equations is very similar to balancing skeleton equations with one extra step… …______________________________________________ _______________________________________________ Word equation: Iron (III) oxide + Hydrogen  Water + Iron reactants products ***Notice that common names are used (water) as well as the diatomic molecule Hydrogen*** Skeleton equation:

try and balance it yourself… Let’s Balance It! H2 + Fe2O3  H2O + Fe H= 2 Fe = 2 O = 3  H = 2 Fe = 1 O = 1 Counting the atoms on each side of the equation shows us that this skeleton equation is not balanced – try and balance it yourself… Balanced equation:

Hints for Doing Word Equations Word equations require careful examination to be written correctly. Always check your exam booklet for the ________________________of some of the covalent compounds (also called _____________________) These are two that you will need to memorize: Methane = _______ Ammonia = ________ The chemical _________ is used for most elements ________________. E.g. If you see _________ in a word equation it is referring to ______ The ___________________ are the others you need to memorize: E.g. If they said hydrogen in the equation they are referring to _____________________________ The others that we needed to remember were: ______________ ______________________________________________________