Describing Matter

Physical Properties

Any characteristic of matter that can be observed without changing the substance.  Color, size, shape, density, melting point and freezing point are some physical properties.  Some physical properties are measure, while others are measured.

Physical Changes

A substance may pick up energy or give off energy causing it to change from a liquid to a gas or vice versa.  Although this occurs, the identity of the substance has not changed, just its physical characteristic.  A change in size shape or state is a physical change. It still retains all of it’s properties, just in a different form.  Physical changes can be used to separate matter. Saltwater can be changed to salt and water if the water is evaporated off.

Chemical changes

A change in one substance into that of another substance is a chemical change.   Iron, if left in contact with oxygen becomes iron oxide. The iron oxide has different properties than the original iron or oxygen.

Chemical properties

A chemical property is characteristic of a substance that indicates whether it can undergo certain chemical changes.  An example is flammability, or corrosiveness, sensitivity to light.

The Conservation of Mass

Matter is neither created nor destroyed.  This law explains that no matter what happens to a substance here on Earth, when something causes a change in state, there is just as much matter before a change as there is after.

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