Warm Up 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

Unit 3-1 The Periodic Table

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

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

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

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-

The Periodic Table

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

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

Average Atomic Mass and Mass Number Name of Atom Abundance Percent % Mass x Percent Lead x 0.014= Lead x 0.241= Lead x 0.221= Lead x 0.524= What is the average mass of Lead? Based on the given stable isotopes

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