1. Atoms & Elements August 26, 2011

2. Atoms Have 3 subatomic particles – Protons, neutrons, electrons Nucleus – Protons and neutrons – # of protons never changes Electron Cloud – Electrons only (negative) – Outer most electrons are valence electrons

3. What is an element? Pure substance – only 1 kind of atom – Think of the same color and flavor of M&Ms All plain, green M&Ms would be one type of atom Each element has a specific # of protons – The atomic # is the # of protons Lithium’s atomic # is 3. Lithium has 3 protons. The amount of protons is the same as the amount of electrons. – Lithium has 3 electrons, too.

4. Neutrons are nutty…. The amount of neutrons can change – Do NOT use these to figure out what element you have. – Same element with different neutrons = isotope Neutrons keep the atom stable How can you figure out how many neutrons you have? Atomic Mass – Atomic Number = # of neutrons

5. Electrons If you know the amount of electrons, it’s the same as the protons…. So…….. You can figure out which element it is! Why? Because # of protons = the Atomic # of an element!

6. Periodic Table Lists all known elements Atomic # = number of protons (or electrons) Atomic mass = average weight of 1 atom Its location will tell you if it’s a metal, nonmetal or metalloid (we’ll do this later…)

7. Today’s Activity Determine which element you have by the information you are given. You will have 2-3min with each card.