chem101 pt1

Definition of Matter

  • Matter: Anything that has mass and takes up space (has a volume).

Classification of Matter

  • Matter can be classified into various categories:

    • Elements

    • Compounds

    • Mixtures

    • Solutions

Differentiated Classification

  • To classify matter, one must ask a series of questions:

    1. Can it be physically separated?

    • If YES: It is a Mixture.

    • If NO: Proceed to the next question.

    1. Is the composition uniform throughout?

    • If YES: It is a Homogeneous Mixture.

      • Examples: Air, Gatorade

    • If NO: It is a Heterogeneous Mixture.

      • Examples: Pizza, milk (colloids), muddy water (suspensions)

Types of Mixtures

  • Heterogeneous Mixtures:

    • Definition: Do not look the same throughout; components can be physically separated.

    • Examples: Pizza (distinct toppings), mud (solid particles suspend in liquid).

    • Characteristics:

    • Can be separated by physical means such as filtration or evaporation.

    • The scattering of light when passed through a mixture is known as the Tyndall Effect.

    • When a beam of light passes through, it scatters, making the mixture visible (as seen in fog).

  • Homogeneous Mixtures:

    • Uniform in composition throughout.

    • Examples: Solutions like salt water, air.

Pure Substances

  • A Pure Substance has a uniform, unchanging composition.

  • Characteristics of Pure Substances:

    • Every sample has exactly the same characteristic properties and composition.

    • Pure substances can be classified as:

    • Elements:

      • Found on the periodic table.

      • Cannot be broken down into simpler substances by physical or chemical means.

      • Taking a nuclear reaction to break down an element is necessary, which will yield the smallest particle of an element (the atom).

    • Compounds:

      • Combinations of two or more elements chemically bonded.

      • Breaking down Compounds: A chemical change (which will be discussed soon) is necessary to separate compounds back into their individual elements.

Physical Changes and Separation

  • A Mixture is simply a combination of two or more pure substances that retain their individual chemical properties.

  • A Physical Change is required to combine pure substances into a mixture and later separate them back into pure substances.

Examples of Physical Separation Methods

  • Filtration: Separating a solid from a liquid using a filter paper.

  • Evaporation: Allowing a liquid to evaporate off to leave behind a solid residue.

  • Distillation: Separating liquids based on their different boiling points.

  • Magnetism: Using a magnet to separate magnetic materials from non-magnetic ones.

  • Chromatography: Separating components based on movement through a medium.