Conservation of matter

Chemical Reaction

A reaction in which one or more substances are changed to new substances

Reactants

Substances that are about to react

Products

New substances produced

Law of conservation mass

Total starting mass of all reactants equals the total final mass of all products

Chemical equation

uses chemical formulas and symbols to describe a chemical reaction and the product it produces

what does the big arrow symbol mean

produces or yields

+

plus

(s)

Solid

(l)

liquid

(g)

gas

(aq)

Aqueous (solid dissolved in H20)

Heat arrow

Reactants heated

Light arrow

Reactants exposed to light

Elec arrow

Electric current

tiny arrow

Applied to reactants

Coeffcients

Numbers which represent the number of units of each substance in a reaction

Subscripts

Numbers which represent the number of atoms in a molecule of a particular element

Balanced chemical equations

Have the same number of atoms of each element on both sides of equation

What should you never change when balancing a chemical equation

the subscripts

What should you change when balancing a chemical equation

The coefficient in front of the compounds needing balanced

Step one to balancing a chemical equation

Write a chemical equation for the reaction using formulas and symbols - make sure reactants are on the left side and the products are on the right side

Step 2 to balancing a chemical equation

Count the atoms in reactants and products

Step 3 to balancing a chemical equation

Choose the coefficients that balance the equation

Step 4 to balancing a chemical equation

Recheck the number of each atom on both sides and adjust the coefficients if necessary