1. Elements It has to be on the Periodic Table. Elements are “pure” meaning they cannot be broken down chemically.

2. Periodic Table period group Group 1: alkalis Group 17: halogens Group 18: Noble Gases

3. Atomic Math Atomic number = the number of protons Atomic mass = # of protons + # of neutrons o So # neutrons =?

4. Element vs. Compound Elements found in nature is on the Periodic Table of the Elements contains only 1 element some needed for life smallest part of an element is an atom Examples: carbon, oxygen, iron Compounds found in nature has 2 or more elements some needed for life smallest part of a compound is a molecule created by a chemical reaction Examples: water, carbon dioxide

5. Examples of Chemical Properties flammability (it can burn) reactivity to oxygen (corrosion) reactivity to light reactivity to water reactivity to electricity reactivity to acid

6. Signs of a Chemical Change releasing a gas, bubbling a change in temperature forming a precipitate (a solid) a change in color reacting with oxygen (burning or rusting) giving off light making a noise (explosion) not reversible

7. Law of Conservation of Mass Says the total mass before the reaction is the same as the total mass afterwards. No matter is created or destroyed in a chemical reaction!

8. Drawing an Atom! The atomic number = # of protons = # of electrons The atomic mass = total # of protons and neutrons in nucleus. Step 1: Find the atomic mass for your element. Draw that many circles for your nucleus. Pack them close together! Step 2: Find the atomic # for your element. Color that many circles for your protons. Spread them around the entire nucleus. Step 3: Color the rest of your nucleus as neutrons. Step 4: Draw the electrons around the nucleus, completely surrounding it. The number is the same as the number of protons.