Unit 5: Balancing Chemical Equations

Comprehensive vocabulary flashcards covering key definitions, reaction parts, the Law of Conservation of Mass, and rules/strategies for balancing chemical equations from Unit 5 Physical Science notes.

Chemical Equation

A representation that describes what happens in a chemical reaction.

Reactants

The substances you start off with in a chemical reaction, located on the left side of the equation.

Products

The substance or substances you end up with in a chemical reaction, located on the right side of the equation.

Yield

Represented by an arrow ($\rightarrow$) in a chemical equation; functions like the equal sign in a math equation.

Law of Conservation of Mass

A scientific law stating that in a chemical reaction, the mass of the reactants equals the mass of the products; matter is never created nor destroyed, but simply changed from one form to another.

Balanced Chemical Equation

A chemical equation in which the mass of the reactants equals the mass of the products, meaning the number of atoms of each element is equal on both sides.

Coefficient

A whole number placed in front of a chemical formula that can be changed to balance the number of atoms of each element on both sides of a chemical equation.

Subscript

A number written below and to the right of an element's symbol indicating the number of atoms; you cannot change subscripts when balancing an equation.

Molecule

A neutral group of two or more atoms held together by chemical bonds.

Compound

A substance formed when two or more different chemical elements are chemically bonded together.

Balancing Chemical Equations

The process of using coefficients so that both sides of a chemical equation have equal amounts of each type of atom.

Balancing Tip #1

Save elements like $H$ and $O$ for last when balancing, and try changing a different element first.

Balancing Tip #2

Always slash your numbers when you make a change (do not erase) so that you can track your progress.

Balancing Tip #3

Elements that stand on their own are easy to change because they are not bonded to anything else.