Chemistry: Matter

Elements
● Elements are pure substances that cannot be changed into simpler substances.
● Elements are composed of one kind of atom.
● Examples: Hydrogen, Oxygen, Carbon

Compounds
● Compounds are pure substances that are composed of two or more atoms that are chemically combined.
● Compounds can only be changed into simpler substances called elements by chemical changes.

Mixtures
● Mixtures are composed of two or more different substances that retain their own individual properties and are combined physically (mixed together).
● Mixtures can be separated by physical means (filtration, sifting, or evaporation).
● Mixtures may be heterogeneous or homogeneous.
          ○ In a heterogeneous mixture, which is not uniform throughout, the component substances can be visibly distinguished.
          ○ In a homogeneous mixture, which is uniform throughout, the substances are evenly mixed and cannot be visibly distinguished. The particles of the substances are so small that they cannot be easily seen. Another name for a homogeneous mixture is a solution. Examples: Rock, Air, Blood, Italian Salad dressing, Ocean water