Mecanics of Chemical Equations

Test review

Reactants, indicating heat products and coefficients and catalysts

" Substances (elements and/or compounds) called reactants are changed into other substances (compounds and/or elements) called products.

an arrow is used to indicate that a chemical reaction has taken place.


The chemical equation that represents this reaction is written like this:

The 2 in front of the oxygen gas and the 2 in front of the water vapor are called the reaction coefficients. They indicate the number of each chemical species that reacts or is formed.

Methane and oxygen (oxygen is a diatomic — two-atom — element) are the reactants, while carbon dioxide and water are the products.

A lot of reactions are exothermic. Some reactions, however, absorb energy rather than release it. These reactions are called endothermic reactions."

States of matter


highly charged particles with extremely high kinetic energy.