U3S10 Describing Chemical Reactions - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the lesson on describing chemical reactions and conservation of mass.

Chemical equation

A shorthand that uses chemical symbols and molecular formulas to show what occurs during a chemical reaction.

Reactants

The chemicals present before the reaction begins.

Products

The chemicals present after the reaction.

Yields

The word used on the arrow to indicate that a reaction forms the products (i.e., 'react to form').

Plus sign

Indicates that the chemicals exist separately on each side of the equation.

Arrow (→)

Indicates the direction from reactants to products in a chemical equation (read as 'produces' or 'yields').

Coefficient

A number placed in front of a substance to indicate how many molecules participate in the reaction.

Subscript

A smaller number written below the normal line of text in a formula, indicating how many atoms of an element are in a molecule.

Chemical formula

A combination of element symbols and subscripts that shows the composition of a substance (e.g., CH4, CO2, H2O).

Law of conservation of mass

Mass is conserved; the same amount of mass is present before and after a chemical reaction.

Balanced equation

An equation in which the number of atoms for each element is the same on both sides.

Count atoms

The process of tallying the number of atoms of each element in reactants and products to ensure conservation.

Precipitate

A solid that forms and settles out of solution during a reaction (e.g., PbI2).

Example reaction CH4 + 2O2 → CO2 + 2H2O

Methane and oxygen react to form carbon dioxide and water.