“The secret of getting ahead is getting started.” Do Now When the bell rings After the bell (2 min) In your seat: With pen/pencil With Notebook With Handout (from last class) Silent and ready for Do Now Respond to the following: “The secret of getting ahead is getting started.” -Mark Twain Still needs Do Now

Agenda  Do Now (5 min) Announcements/Test Scores (5 min) Reflection (5 min) Remediation Topic (5 min) Warm Up (5 min) Highlights of atomic theory history (20 min) Theory v. Law (5 min) Independent Practice (10 min) Exit Slip (5 min) Closing (2 min) Agenda

Remediation Topic: How? What? C – None H – Raise hand A – Identifying Lab Equipment M – None P – Answering questions to the right, recording responses on left page, discussing with group each prompt Identify the use of each piece of lab equipment (use your reference sheet to guide you) Graduated cylinder Erlenmeyer Flask Graduate beaker Tongs Dropper

The History of the Atom Day #2 Objectives: Differentiate between theory and law Understand the history of the atomic theory Create a timeline that shows the changes in the atomic theory over time Summarize the results from Rutherford’s experiment and identify the role of the cathode ray in the discovery of the atom

Warm Up How? What? (5 min) Dalton Chadwick Thomson Bohr Rutherford C – Whispers H – Raise hand A – Answer with group, M – None P – Record responses on reverse side of page. Using your notes from last class place the following list of key contributors to atomic theory in order of appearance Dalton Chadwick Thomson Bohr Rutherford Schrodinger Heisenberg Milliken Democritus de Broglie Seaborg

Our Timeline 1941-1951: Seaborg discovers transuranium elements 400 BC: Democritus theorizes the concept of “atomos” 1911: Rutherford’s Gold Foil Experiment (+ nucleus) 1930: Schrodinger’s wave model 1897: Thomson’s Cathode Ray Tube (electron) 1923: De Broglie discovers wave nature of electrons 1909: Millikan’s Oil Drop Experiment (electron is negative) 1927: Heisenberg’s Uncertainty Principal 1803: John Dalton’s atomic theory The Father of Modern Atomic Theory 1932: Chadwick discovers Neutron 1922: Bohr’s Model

What Is An Atom? Watch the following video: Answer the following: Bill Nye Answer the following: If atoms are mostly empty space, why don’t they break when we stand on them? What is in the nucleus? How far are electrons from the nucleus? What do you get when you combine atoms? How can you demonstrate the spaces between molecules of water? What Is An Atom?

Putting it Together 4 Key Components we need to understand Law of Definite Proportions Rutherford’s experiment JJ Thomson’s Cathode Ray Tube Experiment Continuous Development Putting it Together

Law of Definite Proportions Also known as Proust’s Law Definition: When two elements combine to form a compound, they do so in a definite proportion by mass. Ex: H2O = 2:16  1:8 Mass of Hydrogen: 1 amu x 2 (2 atoms of H) Mass of Oxygen: 16 amu Law of Definite Proportions

JJ Thomson’s Cathode Ray Tube Cathode Ray Tube Experiment Discovered the electron JJ Thomson’s Cathode Ray Tube = =

Rutherford’s Gold Foil Experiment Discovered the positively charged nucleus Rutherford Animation Rutherford’s Gold Foil Experiment Prediction Reality

Continuous Development Science builds upon discovery Every new development in our understanding came by building on or disproving a previous model Our atomic model is only built on 200 years of science It is not complete (see Quarks) Continuous Development

Activity: Independent Practice How? What? 10 minutes  Discuss for 5 minutes  Verify & Review All rows and columns add up to the same number C – None H – Raise hand A –Answering questions about atomic theory history M – None P – Recoding answers on provided page, head up, reading and thinking through all questions, discussing with group

Exit Slip How? What? (5 min) C – No talking H – Raise hand A – Taking exit slip M – In seat P – Completing exit slip without notes and turning in If you finish early, summarize what you learned at the bottom of your notes OR answer today’s guiding question

Forgetting to stretch is a bear. Closing What are 3 key takeaways from today and yesterday? Complete the 4 Stretch questions Be ready to discuss the structure of the atom next class