Chemistry Definitions

Flashcards for key vocabulary and laws in chemistry.

Atom

The basic building block of matter.

Molecule

Composed of two or more atoms.

Compound

Composed of many different types of atoms; not pure element.

Pure Substance

A substance with only one kind of material (element or compound).

Homogenous Mixture

A mixture that is uniform throughout.

Heterogenous Mixture

A mixture that is not uniform throughout.

Chemical Property

Describes how a substance reacts with other substances (e.g., acidity, flammability).

Physical Property

Property that can be observed without changing the identity of the substance (e.g., color, melting point).

Extensive Property

A property that depends on the amount of matter (e.g., mass, volume).

Intensive Property

A property that does not depend on the amount of matter (e.g., color, density).

Solid

Definite shape and volume, particles tightly packed.

Liquid

Definite volume but no definite shape, particles can slide past each other.

Gas

No definite shape or volume, particles move freely and are far apart.

Hypothesis

A testable prediction or explanation.

Theory

A broad explanation supported by lots of evidence.

Law

Describes a consistent natural phenomenon, but doesn't explain why.

Qualitative

Descriptions without numbers (e.g., color, texture).

Quantitative

Involves numbers (e.g., mass, temperature).

Accuracy

How close a measurement is to the true value.

Precision

How consistent repeated measurements are.

Density

Mass per unit volume.

Conservation of Mass

Mass is neither created nor destroyed.

Law of Definite Proportions

A compound always has the same ratio by mass.

Law of Multiple Proportions

When two elements form different compounds, the mass ratios are whole numbers.