Elements, Compounds, Mixtures, and Chemical Laws

Vocabulary flashcards covering atomic and molecular representations, classification of matter, Law of Conservation of Mass, Percent Composition, and the Law of Definite Proportions.

Classification of Matter Diagram

Visual representation showing atoms as single spheres, molecules of elements as identical spheres joined together, and molecules of compounds as different spheres joined together across elements, mixtures, and compounds.

Atoms

Particles represented in particle diagrams by single spheres, where spheres of the same size and colour represent atoms of the same element.

Molecules

Structures represented in particle diagrams by two or more spheres joined together.

Molecules of Elements

Molecules represented in particle diagrams by two or more spheres of the same size and colour joined together.

Molecules of Compounds

Molecules represented in particle diagrams by two or more spheres of different sizes and colours joined together.

Law of Conservation of Mass

The law stating that matter is neither created nor destroyed by chemical reactions or physical changes, meaning the mass of the system and the number and type of atoms remain unchanged.

Magnesium Combustion Reaction

A balanced chemical reaction $2Mg + O_2 \rightarrow 2MgO$ demonstrating that reactant atom counts ($2 \times Mg$, $2 \times O$) equal product atom counts ($2 \times Mg$, $2 \times O$).

Percent Composition

The mass percentage of each element in a compound, such as Potassium Permanganate ($KMnO_4$) with molar mass $158\,g$ consisting of $24.7\%$ $K$, $34.8\%$ $Mn$, and $40.5\%$ $O$.

Joseph Proust

The French chemist who proposed the Law of Definite Proportions in $1799$.

Law of Definite Proportions

A law stating that a compound is always composed of the same elements in the same proportion by mass, regardless of sample size, and that the mass of the compound equals the sum of the masses of its constituent elements.

Constant Composition

Another term for the Law of Definite Proportions, stating that a given compound always contains elements in a certain proportion by mass.

Reactants

The starting substances present before a chemical reaction occurs.

Products

The new substances formed as a result of a chemical reaction.