Unit 7 Chemistry Vocab

Balanced Equation

A balanced chemical equation occurs when the number of the different atoms of elements in the reactants side is equal to that of the products side. Balancing chemical equations is a process of trial and error.

Reactants

Substances initially present in a chemical reaction that are consumed during the reaction to make products.

Chemical Reaction

The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants.

Products

The substances that result from this recombination of atoms are called the products of the reaction. When chemical reactions are written down, the reactants are written on the left side, in a similar manner to a math equation; one reactant plus another.

Coefficient

a multiplier or factor that measures some property.

Oxidation Number

a number assigned to an element in chemical combination that represents the number of electrons lost (or gained, if the number is negative) by an atom of that element in the compound.

Combustion Reaction

a reaction in which one of the reactants is oxygen. ▪ The other reactant is usually a hydrocarbon.

Combination (Synthesis) Reaction

a reaction where two or more elements or compounds (reactants) combine to form a single compound (product).

Catalyst

a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.

Double Replacement (Displacement) Reaction

a type of chemical reaction where two compounds react, and the positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products.

Single Replacement (Displacement) Reaction

a type of oxidation-reduction chemical reaction when an element or ion moves out of one compound and into another - that is, one element is replaced by another in a compound.

Activity Series of Metals

a useful guide for predicting the products of metal displacement reactions. For example, placing a strip of zinc metal in a copper(II) sulfate solution will produce metallic copper and zinc sulfate, since zinc is above copper on the series.

Oxidation-Reduction (Redox) Reaction

a useful guide for predicting the products of metal displacement reactions. For example, placing a strip of zinc metal in a copper(II) sulfate solution will produce metallic copper and zinc sulfate, since zinc is above copper on the series.

Half Reaction

either the oxidation or reduction reaction component of a redox reaction. A half reaction is obtained by considering the change in oxidation states of individual substances involved in the redox reaction.

Law of Conservation of Mass

states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.

Decomposition Reaction

the separation of a chemical compound into elements or simpler compounds. It is sometimes defined as the exact opposite of a chemical synthesis. Chemical decomposition is often an undesired chemical reaction.

Chemical Equation

the symbolic representation of a chemical reaction in the form of symbols and formulae, wherein the reactant entities are given on the left-hand side and the product entities on the right-hand side.