1. O: You will be able to explain the difference between elements and compounds. Do Now: Everything in the world is made up of atoms, how many different types of atoms are there? Why did you say that?

2. Elements An element is a pure substance that cannot be separated into simpler substances by physical or chemical means.

3. A pure substance is a substance in which there is only one type of particle. Gold is only made of gold atoms. Oxygen is only made of oxygen atoms.

4. The smallest particle of an element is an atom. Every element has its own type of atom.

5. Thought Questions 1. If we only have 121 elements, how do we have so many different things on the planet? 2. What do you think makes the elements atoms different from each other?

6. Compounds A compound is a pure substance composed of two or more elements that are chemically combined. The elements undergo a chemical change and make a totally new substance.

7. The properties of a compound can be totally different from the properties of both the elements that made it.

8. Molecules The smallest piece of a compound is a molecule. A molecule is a groups of atoms chemically bonded together that act as a single unit.

10. The ratio of elements in a compound always has to be the same.

11. What is the relationship between atoms, molecules, elements, and compounds?

12. Mixtures Mixtures are two or more substances mixed together but NOT chemically combined. The substances keep their own properties. It can be seperated.