1. Warm Up9-21-15 1. Convert 25 mg to g 2. How many neutrons are in 85 Kr? 3. Write the short hand electron configuration for Indium and Bromine Homework Sept 23 - Test unit 2 Sept 23 - Notebook check (6 days of notes for unit 2) Agenda Turn in WS Test review Notes Unit 3-1 WS Subatomic heavyweights

3. Unit 3-1 The Periodic Table

4. How would you organize the following (16) items? Wrench Pliers Clamp Nuts Drill Screw driver Box cutter allen wrench

6. Unit 3-1 Periodic Law  Periodic law - periodic table is organized based on the atomic #, chemical & physical properties of the elements  Mendeleev is the creator of the periodic table used atomic mass

7. The Periodic Table  Group or family  A vertical columns  Elements in a group share the same chemical properties  Period  A horizontal rows  Elements in the same period have the same number of energy levels

8. The Periodic Table  Elements’ chemical properties are determined by the number of valence electrons  Valence electrons are electrons that are in the outermost energy level of an atom (in the S and P orbital only) e-

9. The Periodic Table

10. Average Atomic Mass vs. Mass Number What is the mass of neon element?

11. Average Atomic Mass vs. Mass Number  The average atomic mass is the average of the mass numbers of all the isotopes of that element.  Molybdenum probably has more isotopes with a mass number of 96, rather than 95

12. Average Atomic Mass and Mass Number Name of Atom Abundance Percent % Mass x Percent Lead-2041.4204 x 0.014= 2.856 Lead-20624.1206 x 0.241= 49.646 Lead-20722.1207 x 0.221= 45.747 Lead-20852.4208 x 0.524= 108.992 What is the average mass of Lead? Based on the given stable isotopes

13. Assignments  Summary  WS Subatomic heavyweights due today  Study for Unit 2 test Wednesday