1. I. Bohr’s Model / Energy Levels A. Def – a specific area where an electron is likely to be. nucleus 2 electrons 8 electrons 18 electrons 32 electrons e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e- e- e- e- e- e- e- e- e- e-

2. Chapter 4 Lesson 2 “A Tour of the Periodic Table”

3. I. Organization of the P.T. A.Periodic Law 1.Def – Elements are arranged according to properties. 2.Ex: Group 1 Elements Video 3.Periods – horizontal 4.Group – Vertical a. Aka family

5. II. Ions A.Def – an atom that gains or loses electrons. Will have a negative or positive charge. B.Ex: Fluorine (pg. 115) F 2e 7e e 8e What kind of charge will fluorine have now as an ion? 1-

6. III. Atomic Number A. Def – the # of protons in an atom’s nucleus. B. On P.T. – located right above the chemical symbol *Protons dictate the type of element we have* *Electrons always equal the # of protons in a neutral atom*

7. IV. Mass Number A. Def – The sum of protons and neutrons in the nucleus of an atom. 1. On P.T. – bottom number -round up/down 2. Ex: What is the mass number of the following elements? CarbonOxygen IronCalcium SodiumZinc 12 56 23 16 40 65

8. 3. Mass # = Protons + Neutrons 4. How many Neutrons on average are found in the following elements? BoronFluorine SiliconCopper SilverGold 118 14 6 61 10 35

9. V. Isotope A. Def – An atom that has a different number of neutrons. 1. Does not affect the element 2. Only changes the weight of the element 3. Ex: Boron-10 and Boron-11 p p p p p n n n n n n 5 protons 5 neutrons6 neutrons This means the mass # Boron-10Boron-11

10. 4. How many neutrons do the following isotopes have? Oxygen-14 Titanium-50 Magnesium-22 Potassium-43 Aluminum-23 Iodine-130 6 28 10 24 10 77

11. VI. Average Atomic Mass A. Def – average mass of all isotopes of one element combined. 1. Found on P.T. underneath chemical symbol. 2. Ex: Carbon = 12.011 “Carbon has 3 known isotopes. Carbon-12, 13, and 14. Carbon-12 makes up 99% of all carbon on earth. Carbon-13 and 14 make up 1%.” Why?