2.  Matter made up of one type of atom or molecule

3.  A pure substance in which the atoms of two or more elements are linked together chemically

4.  The smallest unit of a compound that has all the properties of that compound

5.  A set of symbols showing what atoms make up a compound

6.  A small number that says how many atoms of an element are in a molecule

7.  A combination of two or more pure substances that can be separated by physical means

8. Elements form Compounds  All ordinary substances are made up of atoms  These substances can be classified based on how the atoms are arranged  Three groups of matter: elements, compounds and mixtures  Elements and compounds are examples of pure substances

9.  A pure substances is made up of only one kind of atom or molecule and can not be separated into its parts by physical means  The atoms of the elements that make up a compound bond to one another  Bonding takes place when atoms join by sharing or exchanging electrons  Compounds can only be separated by chemical means

10.  The elements that form a compound do not keep their individual properties  Every compound has a definite composition and its own chemical formula

11.  The substances that form a mixture are not bonded together.  This means that the parts of a mixture retain their individual identities and properties  A mixture that is unevenly mixed is a heterogeneous mixture  A mixture that is evenly mixed throughout is a homogeneous mixture  Air is a mixture of gases, ocean water is another mixture  All mixtures can be separated using various physical means

12. 1. Soil is made up of pieces of rocks, wood, decayed plants, and many other minerals. What is soil? a. an atomc. a compound b. an elementd. a mixture

13. 2. What is a pure substance that can be separated into two or more simpler substances by chemical means? a. an element c. a formula b. a compoundd. am atom

14. 3. A molecule of carbon dioxide is shown above. Based on the drawing of the molecule, what is the chemical formula for carbon dioxide? a. COc. C 2 0 b. 2COd. CO 2

15. 4. The chemical formula for glucose is C6H12O6. How many different elements make up one molecule of glucose? a. 1c. 12 b. 3d. 24