Elements, Compounds, and Mixtures

Pure substances

A sample of matter that has definite chemical and physical properties.

Elements

Pure substances that cannot be separated into simpler substances by physical or chemical means.

Compounds

Pure substances composed of two or more different elements joined by chemical bonds.

Mixtures

A combination of two or more pure substances that are not chemically combined.

Homogeneous mixture

A mixture in which the components are evenly distributed and appear uniform throughout.

Heterogeneous mixture

A mixture in which the components are not evenly distributed and can often be seen.

Suspensions

Heterogeneous mixtures in which particles are dispersed in a liquid or gas and will eventually settle out.

Solutions

Well-mixed homogeneous mixtures that appear to be a single substance.

Filtration

A technique used to separate heterogeneous mixtures composed of solids and liquids using a porous barrier.

Distillation

A method to separate homogeneous mixtures based on differences in boiling points.

Crystallization

The process that results in the formation of solid particles from a solution.

Centrifugation

A technique using rapid spinning to separate materials based on their densities.

Chromatography

A separation technique based on different rates at which components move across a surface.

Decantation

The process of separating particles from a liquid by allowing solids to settle and pouring off the liquid.