Classifying Matter

States of Matter

Purity

Matter can also be classified by purity and composition. This classification is based on how the components in a sample are held together, whether a sample can be broken down into smaller components, and how the sample can be broken down, if at all. Sample are first divided into substances and mixtures. Substances can be further subdivided into elements and compounds whereas mixtures can be subdivided into homogenous and heterogenous.

Substances

Elements

  • Elements cannot be broken down by either physical or chemical changes. Under this classification scheme, elements are the purest form of matter.

  • Example: A block of aluminum (The block only contains one type of particle, aluminum, and cannot be broken down any further by physical or chemical methods.)

Compounds

  • Compounds are formed by chemically bonding two different elements together.

  • Elements are combing in specific ratios

  • It is possible to break down some compounds into elements using chemical reactions.

  • Example: Water (Water consists of two elements, hydrogen and oxygen. The two elements cannot be separated by a physical process, but can be separated using a chemical reaction)

Mixtures

  • Mixtures are the combination of two or more substances (elements and/or compounds)

  • Elements and compounds mixed in this way are not chemically bonded.

  • Mixtures can be separated using physical properties/changes

Homogenous Mixtures

  • Substances are mixed and distributed uniformly

  • Example: Salt dissolved in water (When the salt is dissolved in water, the salt particles will evenly disperse into the water).

Heterogenous Mixtures

  • Substance are mixed in such a way that the distribution is not uniform

  • Example: Water and sand (The sand will sink to the bottom of the mixture. Even if stired vigoursly, the sand will start to settle).

Diagram of purity heirarchy