Matter:
Matter can be classified as a solid, liquid, gas, or plasma:- Solids: have definitive volumes and shapes.
- Liquids: have distinct volumes, but their shape depends on the container they are contained within.
- Gases: have no fixed volume or shape; they assume the shape of the container they are in.
Note: Gases are highly compressible while liquids and solids aren't.
Matter can also be classified according to its composition:
Matter can also be classified according to its composition:
- Atoms: The building blocks of all matter.
- Elements: Made from the same kind of atoms. An element can't be decomposed into simpler substances by chemical means.
- Pure substance: Matter that has distinct properties and a composition that doesn't vary from sample to sample. A pure substance can either be an element or a compound. Very few pure substances exist in our natural environment.
- Compounds: Made up of 2 or more different kinds of atoms. Compounds can be broken down into simpler substances by chemical means but not by physical means. Water for example can be decomposed into its elements: Hydrogen and Oxygen.
If 2 or more elements react to give a compound, the properties of the elements are not retained in the compound. Compounds are represented by chemical formulas which show their elemental composition:
Mixtures:
Most matter occurs in form of mixtures of elements and/or compounds. The components of a mixture retain their own identity. Saltwater tastes salty but also has properties similar to pure water.
Example: Air consists of many elements (nitrogen, oxygen, and argon which makeup 99% of the atmosphere). Soil on the other hand is a complex mixture of many compounds.
Two Types of Mixtures:
- Heterogeneous: A mixture that doesn't have the same composition, properties, and appearance throughout (rocks, soil).
- Homogeneous: A mixture which is uniform throughout. Homogeneous mixtures are called solutions (cup of tea).
Below in figure 1 is a good chart for the classification of matter:
