3 3 Compounds and Mixtures Vocabulary word formula

3. 3 Compounds and Mixtures Vocabulary word formula substance compound mixture Definition

3. 3 Compounds and Mixtures The food we eat, the materials we use and all matter can be classified by compounds or mixtures. • Substance- matter that has the same composition and properties throughout. An element such as a bar of gold is a substance. • Compound- a substance whose smallest unit is made up of atoms of more than one element bonded together. • Properties that are different from the elements that make them up. Ex: water, H 2 O. • Mixtures- when two or more substances (elements or compounds) come together but don’t combine to make a new substance. • Ex: mixing sand water together does not change its identity. They are not chemically bonded together.

3. 3 Compounds and Mixtures Compounds Have Formulas • Chemical formulas: • Which elements make up a compound • The subscript number written below and to the right of each element’s symbol tells how many atoms of each element are present • Ex: H 2 O has two atoms of hydrogen and one atom of oxygen. • Ex: H 2 O 2 has two atoms of hydrogen and two atoms of oxygen. • *Propane has three carbon and eight hydrogen atoms. What is its chemical formula?

3. 3 Compounds and Mixtures Homogeneous Mixtures • Homogenous means “the same throughout. ” • You cannot see the different parts in this type of mixture Heterogeneous Mixtures • Larger parts that are different from each other • You can see the different parts in this type of mixture • Ex: sand water