Chemistry Fundamentals and Atomic Theory Vocabulary

Chemistry

The study of the composition, properties, and transformations of matter; considered the central science.

Scientific Method

A cyclical approach used to gather information and form explanations.

Observation

A statement describing what you see or hear.

Scientific Law

An equation or generalization that describes what happens without explaining why.

Hypothesis

A tentative explanation that leads to further experiments.

Theory

A tested explanation that can be proven wrong.

Matter

Anything that occupies space and has mass.

Mass

A measurement of how much matter is in an object.

Weight

The force of gravity acting on an object.

Chemical Reaction

A transformation that alters the chemical composition of substances, where reactants yield products.

Decomposition Reaction

A chemical reaction in which a single substance is changed into two or more other substances.

Element

A pure substance composed of one type of atom that cannot be decomposed into simpler substances.

Compound

A substance formed when two or more atoms of different elements combine after a chemical reaction in a fixed proportion by mass.

Pure Substance

Matter with a constant composition, classified as either an element or a compound.

Mixture

Matter made of two or more substances combined physically with a variable composition.

Homogeneous Mixture

A mixture that has the same properties throughout, also known as a solution (e.g., sugar in water).

Heterogeneous Mixture

A mixture containing two distinct phases that does not have uniform properties throughout (e.g., oil and water).

Physical Change

A change that alters physical state or mixture formation without changing the chemical makeup of the substances.

Chemical Change

A change in which the chemical makeup of the involved substances is altered to form new substances.

Physical Property

A property of a substance that can be observed without changing its chemical identity, such as conductivity or melting point.

Chemical Property

A property describing a chemical change or reaction that a substance undergoes.

Aqueous State

A physical state denoted by