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