AP Chapter 1

Matter and Measurement

Chemistry

• Chemistry is the study of the properties and behavior of matter.

• Matter is the physical material of the universe and has mass and volume, and therefore density.

Matter

• Elements – composed of a single type of atom.

• Molecules – 2 or more atoms combined chemically to make a substance.

States of Matter

• Gas – no fixed shape or volume – it takes the shape of its container and is compressible.

• Liquid – distinct volume, but no fixed or distinct shape. It takes the shape of its container.

• Solid – definite shape and volume. It’s non-compressible.

Pure Substances

• Pure substances can NOT be broken down by physical means.– Elements can’t be broken down further– Compounds – can ONLY be broken down

by chemical means into their elements.– 2H2O → 2H2 + O2 (using electrolysis)

Mixtures

• Multiple substances are involved in mixtures, each with its own properties.

• Mixtures are separated by physical means based on the properties of the substances in the mixture.– Evaporation– Filtration– Sorting

Mixtures

Homogeneous Mixtures

• The same composition exists throughout the sample.

• Can be liquid or solid

Heterogeneous Mixtures

• Different composition in different areas of the sample.

Physical and Chemical Changes

• Physical Change – changes the physical appearance but not the composition. State changes are physical changes.

• Chemical Changes – changes the composition of the substance and creates a new substance with new and different properties.

SI Base Units

Units of Measurement

Density

Accuracy and Precision

• Accuracy – How close the measured values are to the accepted values.

• Precision – How close the measured values are to each other.