READ: Chemical Formulas

Summary

• Scientists use chemical equations to summarize what happens in chemical reactions. Reactants are placed on the left side of the equation and products are placed on the right. An arrow is used to indicate the direction in which the reaction occurs. Plus signs (+) are placed between multiple reactants or products.
• In chemical equations, reactants and products are represented by chemical symbols and formulas. Numbers called coefficients are placed in front of the symbols and formulas to show how much of each substance is involved in the reaction.
• Chemical equations must be balanced. A balanced equation has the same number of each type of atom on both sides of the equation.
• Burning and other changes in matter do not destroy matter. The mass of matter is always the same before and after the changes occur.
• The law of conservation of mass states that matter cannot be created or destroyed.

Vocabulary

Chemical symbols: one or two letters used to represent every element.
Compounds: combinations of two or more elements.
Chemical formula: an expression that shows the elements in a compound and the relative proportions of those elements.
subscript: a number that is smaller than the normal type and is set slightly below. 
chemical equation: Symbolic representation of a chemical reaction.
law of conservation of mass: Law stating that matter cannot be created or destroyed in chemical reactions.