A description of a chemical reaction that gives the chemical formulas of the reactants and the products of the reaction. Coefficients indicate the number of each molecule present in the reaction. These coefficients can be changed so as not to violate the Law of Conservation of Mass.
Coefficient
Numbers inserted before chemical formulas in an equation to ensure that an equation is balanced.
Combustion Reaction
A chemical reaction between a fuel and oxygen that produces heat and light as well as carbon dioxide and water.
Decomposition
A reaction in which a compound is broken down into simpler compounds or elements.
Double Replacement
Also known as a metathesis reaction. A reaction in which two reactants trade partners. Here's an example: AB + CD → AC + BD.
Electrolysis
The process of driving an electrical current through a reaction mixture.
Endothermic
A process that absorbs heat.
Exothermic
A process that releases heat.
Law Of Conservation Of Mass
The law that states there is no change in total mass during a chemical change.
Physical Change (or Physical Reaction)
A change that does not transform one substance into another substance, such as freezing or melting. That is to say, no new types of molecules are formed during a physical change.
Precipitate
An insoluble substance that has been formed after the conclusion of a reaction.
Product
The compounds that exist after the conclusion of a reaction. It's also the new molecules that are formed as a result of a chemical reaction.
Reactant
The components that exists before a reaction takes place. It's also the molecules present at the start of a reaction that will combine to form the products.
Single Replacement
A reaction in which one component of a compound is replaced by a new component. Here's an example: AB + C → A + BC.
Skeleton Equation
An equation that identifies the reactants and products but the equation is not necessarily balanced.
Stoichiometry
The relationship between the relative quantities of atoms or molecules taking part in a reaction or forming a compound.
Synthesis Reaction
The formation of a complex product from simpler reactants. Here's an example: A + B → AB.
Thermal Decomposition Reaction
A decomposition reaction initiated by heat.
Word Equation
An equation in pure word form with no elemental symbols or numbers.