Chapter 1-6 Concepts: Elements, Pure Substances, Molecules, and Mixtures

A set of vocabulary flashcards covering elements, pure substances, atoms, molecules, compounds, and mixtures based on the lecture notes.

Element

A pure substance consisting of only one type of atom; cannot be decomposed into simpler substances by chemical means. Examples: hydrogen, oxygen, iron, aluminum.

Pure substance

A material with a definite composition that contains only one kind of particle; it can be a pure element or a pure molecule.

Atom

The smallest unit of an element that retains the properties of that element.

Molecule

Two or more atoms bonded together; can be the same element (e.g., O2) or different elements (e.g., CO2, H2O).

Carbon dioxide (CO2)

A molecule with one carbon atom covalently bonded to two oxygen atoms; a pure substance when present as CO2 molecules.

Water (H2O) molecule

A molecule consisting of two hydrogen atoms bonded to one oxygen atom.

Pure substance equals element or molecule

A pure substance is either a pure element (one type of atom) or a pure molecule (a single type of molecule).

Copper

A chemical element; a pure substance made of one type of atom.

Compound

A substance formed from two or more elements in a definite ratio (e.g., CO2, H2O).

Mixture

A substance composed of two or more different substances that are not chemically bonded; components can be elements or compounds.

Lemon juice in water

An example of a mixture; it contains different molecules than pure water.

River or lake water

An example of a mixture; a water sample containing many substances besides H2O.

Two types of substances in chemistry (summary)

Pure substances include elements and compounds; mixtures contain multiple substances not bonded together.