AP Chem Chapter 1

Chemistry is the study of the properties and behavior of matter, in which matter is the physical space consisting of elements.

• These elements consist of atoms that have unique properties, and those properties help chemists define their specialized function.

• The importance of chemistry is for health care, protection of the environment, and the supply of energy for society

To classify matter, there are three stages known as:

• Gas: Has no fixed volume or shape, and can be compressed or expanded to a small or larger volume

  • Has high speeds and collides repeatedly with other molecules or its own container

• Liquid: Distinct Volume based on the container, and can not be compressed

  • Packed closely together, and the rapid movement allows them to slide over one another, allowing liquid to pour

• Solid: Has a definite shape and a define volume, not allowing it to be compressible.

  • Molecules barely move from their fixed positions.

Changes in temperature and pressure can cause a conversion from one state of matter to the other.

A pure substance is a chemical composition that does not change from sample to sample (table salt, water).

• Elements are substances that can not be decomposed further

• Compounds are substances composed of two or more elements

• Mixtures are combinations of two or more substances (element or compound).

The law of definite proportions explains that a compound must always use the same elements no matter what.