1. Matter
2.3
Compounds and Mixture

2. Substances - matter that has the same compositions and properties
Compound - a pure substance whose smallest unit is made up of atoms of more than one element
Examples: water, Hydrogen peroxide, Carbon Dioxide
Compounds need Formulas
Subscripts refer to number of atoms
No subscripts for one atom
Law of Definite proportions - a given compound is always made of the same elements in the same proportion by mass.

3. Mixtures - two or more elements combined that don’t make a new, pure substance
Examples: Air, Cereal, Blood
Uniform mixtures - cannot see the individual parts
Nonuniform mixtures - can see the different parts.
2.3 Pg