HOMEWORK IS WHERE THE REAL LEARNING HAPPENS! ALEKS does not do it all! All homework problems are in the Chem 110 Student Packet GOAL: learn HOW to solve problems Finish these before recitation each week??? GET HELP! TA Office hours (211 Whitmore) Form Study Groups Bring unresolved questions to recitation This work prepares you for Recitation Queries, Angel Quizzes and Exams Mary J. Bojan Chem 110 1
RECITATIONS On Thursdays Small class of ~30 led by your TA Practice solving problems, get help from TA and other students Recitation Query at the beginning of period Based on the assigned homework problems in the student packet. MUST explain how you get answer to get full credit. One question, 3 points 2 more points for attendance and participation Points available: 70 Maximum points possible: 50 No make up for Recitation Queries! Mary J. Bojan Chem 110 2
RECITATIONS On Thursdays (tomorrow) Bring text, student packet, calculator + completed HW Recitation = final preparation for Quiz Quiz questions are similar to Homework problems in syllabus Starting with second week: Angel QUIZ each week due on Thurs at 11:55pm (Tues. on exam weeks) Quiz points available: 140 Maximum Quiz points possible: 100 No make up for quizzes! Mary J. Bojan Chem 110 3
Today: Chapter 2 Introduction to Atomic structure GOAL: What IS the structure of an atom? What are the properties of atoms? REMEMBER: structure affects function! Important questions: Where are the electrons? What is the energy of an electron? Mary J. Bojan Chem 110 4
What is the structure of an ATOM? An atom is made of protons neutrons and electrons COMPONENTS OF ATOMS proton p electron e neutron n mass (a.m.u.) charge (a.u.) Neutral Ion 19 F 9 39 K 19 + Mary J. Bojan Chem 110 5
Isotopes: are atoms with the same atomic number but different number of neutrons For a given element, the number of protons is fixed, but the number of neutrons can vary. atomic number =??? DEFINES 35 Cl 37 Cl 17 17 Mary J. Bojan Chem 110 6
Atomic weight (AW) is also known as average atomic mass. Atomic weights are listed on the periodic table. The Atomic Mass Scale We define: mass of 12 C = exactly 12 amu. 1 amu = 1.66054 x 10-24 g 1 g = 6.02214 x 10 23 amu Using atomic mass units: 1 H weighs 1.6735 x 10-24 g 16 O 2.6560 x 10-23 g. Use ISOTOPE RATIOS to find Average Atomic Masses E.g. 12 C 98.892 % mass = 12 amu 13 C 1.108 % mass = 13.00335 Average mass of C: (0.98892)(12 amu) + (0.0108)(13.00335) = 12.011 amu. Mary J. Bojan Chem 110 7
Problem: no one can see (or weigh) an atom The mole is the connection. Another definition: 1 mole of 12 C has a mass of 12 g What is a mole? 1 mole of anything (atoms, molecules, green peas) = Avogadro s number of them How BIG is a mole? Mary J. Bojan Chem 110 8
MOLE: connection between microscopic (what we don t see: atoms) and macroscopic (what we see) Avogadro s number: nanoscale macroscale 1 molecule of H 2 O 18 g = 1 mol H 2 O Mary J. Bojan Chem 110 9
Back to the atom: What is the structure of the atom? Where are the protons? neutrons? electrons? ~1910 JJ Thompson s plum pudding Model??? Mary J. Bojan Chem 110 10
~1910 Earnest Rutherford tested Thompson s plum pudding Model Rutherford concludes: massive nucleus with electrons orbiting around it. Mary J. Bojan Chem 110 11
Modern View of atom: An atom is almost entirely empty space. 1nm = 10-9 m 10Å = 1nm Å= angstrom Atom Diameter = 0.1-0.5 nm Nuclear diameter = 10-5 nm Atom diameter = 10,000 x nuclear diameter But where ARE the electrons???? Mary J. Bojan Chem 110 12
Practice Recitation Query We will spend the last 10 minutes of class doing a practice Recitation Query Before next class: Do the HW problems on page 24 of your student packet. Finish ALEKs Prep course, transfer to full course and then complete Objective 1 as soon as possible. Read 3.1-2, Chapter 10.1-2 Mary J. Bojan Chem 110 13
Key themes: Overview of Chem 110 structure affects function (properties). How do we know about atoms, etc.? Structure of atom Ch. 3 Properties of Atom Ch. 4 How atoms bond to form molecules Ch. 5 Structure of molecules Ch. 6 and 7 Properties of molecules Ch. 11, 12, 13 Molecules REACT! Ch. 8 and 9 Rules that govern reactions Thermodynamics (think energy) Ch. 10 Equilibrium Ch. 15 Mary J. Bojan Chem 110 14