Chemical Reactions and Balancing Introduction Presentation

The Nature of Chemical Reactions  What indicates that a chemical reaction has happened?

What is a chemical Reaction?  Any process/reaction that produces new materials from the original materials  Change in form in products  Must maintain the same mole ratio through the process while re-arranging matter

Main parts of a chemical reaction  1. Reactants—chemicals that start the reaction  Located on the left side of the equation  A + B   2. Products– substances that are created during the chemical reaction process  Located on the right side of the equation  A + B  AB

State of matter symbols used in reactions  (s)—solid  (l)—liquid  (g)—gas  (aq)—aqueous (solid that has been dissolved in water)  Typically necessary because many solids do not react in the solid state (need free electrons)

Directional and Quantity Symbols  1.  yields or makes used to separate the reactants from products  2. Element on top of an arrow = catalyst  3. + combining

Why do elements react with each other?  Main goal is to have a full valence shell  Accomplished by exchanging valence electrons (Ionic Bonds)  Or by sharing valence electrons (molecule)  Elements need 2 valence electrons (H, He, Li, Be, B) or 8 to be complete

List 4 things that can happen during a reaction

Chemical Equations and Formula Writing  1. Word Equations—use element names to illustrate a reaction  Can be clumsy and difficult to work with on a regular basis  2. Formula Equations—Use element symbols to illustrate a reaction for us  Much quicker and easier to work with

How do I balance chemical equations?  Law of Conservation of mass/matter---tells us that matter cannot be created nor destroyed  In all processes matter is just re-arranged  Must have the same amount of reactants and products  Mass should not be different from one side of an equation to another

What are coefficients?  Whole numbers placed IN FRONT of an element/compound in a chemical equation to balance the reaction  This whole number is distributed to the element/compound it is in front of  All reactions must be balanced