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Chemistry Day 6 Friday, September 13th – Monday,
September 16th, 2019 See last week’s powerpoint for these notes
Chemistry Day 7 Tuesday, September 17th – Wednesday,
September 18th, 2019
Do-Now Title: “Inquiry Demo” 1. Write down today’s FLT 2. What do you think atoms are? 3. What do you think atoms are made of? 4. Draw what you think an atom looks like. Label
your drawing. 5. What tools do you think you would need in order
to discover or study atoms? 6. Underneath your do-now, write “Demonstration
Notes”
Finished? Take out your planner and table of contents.
Demo • Therewillbeasponge,rubbingalcohol,dryice,andasealedglassjar
• Underneathyourdo-now,writeapredictionaboutwhatyouTHINKwillhappen
• Useyourpro-talksentenceframe“Inmyopinion…because…”tomakeapredictionaboutwhatyouTHINKwillhappen.
Demonstration • Wealreadypredictedwhatwewillsee
Observationexpectations:– Watchwithyoureyes– Waituntilthedemonstrationisfinishedtowriteorsayanything
– Summarizein1-2sentencesORasimplediagram
Demo • Now,writedownthreequestionsyouhaveaboutwhatyousaworabouttheexperimentalvariables.
• Questionsshouldbescience-relatedandsomethingyoucannotyetanswer
Demonstration • Partner(s):• Shareeachofyourquestionswitheachother
• Decideasagroupwhichquestionisthe“best”andcouldbeansweredwithadditionalevidence,andeveryoneshouldwriteitontheirpaper.
• Ifitisyourownquestion,simplyputastarnexttoit
Explanation • Now,wewillrewatchthevideowiththeexplanation.
• Remember–thisisapreviewintowhatwearelearning.Wewillgoovertheseconceptsagain.
• Writedown2-3piecesofevidencethatcouldusetohelpexplaintheexperimentoryourquestion.
Conclude • Useyourevidencetotrytoansweryourquestion.Youmayneedtomakeaninference.
• Useoneofthefollowingpro-talksentenceframes:– “Ifwelookatboth….and….Wecanseethat….”
– “Basedontheevidence,suchas…,wecanconcludethat….”
FLT • I will be able to describe early ideas
about the atom by completing Early Atomic Theory Notes A
Standard HS-PS1-8:Developmodelstoillustratethechangesinthecompositionofthenucleusoftheatomandtheenergyreleasedduringtheprocessesoffission,fusion,andradioactivedecay
Notes Protocol • Title your notes & add assignment # • Complete Cornell-style • Copy down all bolded ideas • Noise level 0 • Raise hand to question/comment • Be prepared to pair-share-respond
Early Atomic Theory: Part A
What is an Atom?
What is an Atom? • Atom=thesmallestparticleofanelementthatretainsitsidentityinachemicalreaction
• Anatomisextremelysmall-whatwouldbeneededinorderforpeopletodiscoverit?
A history of the atom
• AncientGreece:PhilosopherDemocritusdidnotdiscovertheatom,buthewasoneofthefirsttosuggesttheirexistence.
A history of the atom • Democritusdescribedatomsasindivisibleandindestructible.
• Washecorrect?Couldhesupporthisideas?
• àTherewasnoevidencetosupportDemocritus’ideas(yet)
John Dalton - 1776-1844 • JohnDaltonwasachemistwhostudiedgases,pressure,andtheexistenceofatoms.
John Dalton - 1776-1844 • JohnDalton=supportedDemocritus’ideawithscientificevidence.
• Cameupwiththeearlyideasforatomictheory...
Dalton’s Atomic Theory 1. All elements are composed of tiny
indivisible particles called atoms
Dalton’s Atomic Theory 2. Atoms of the same element are identical.
The atoms of any one element are different from those of any other element.
Dalton’s Atomic Theory 3. Atoms of different elements can mix or
combine in simple whole-number ratios to form compounds
Dalton’s Atomic Theory 4. Chemical reactions occur when atoms are
separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.
Dalton’s Atomic Theory Note:Not all of Dalton’s ideas were correct...as we will see when we talk about modern atomic theory :)
How Can We Study Atoms? • Atomscanbeseenusingextremelyhighpoweredmicroscopes,suchasscanningtunnelingmicroscopes.
Sample Questions 1. The ancient Greek philosopher credited with suggesting all matter is made of indivisible atoms is A. Plato B. Aristotle C. Democritus D. Socrates
Sample Questions 2. Dalton’s atomic theory improved earlier atomic
theory by a. teaching that all matter is composed of tiny
particles called atoms b. theorizing that all atoms of the same element are
identical c. using experimental methods to establish scientific
theory d. Not relating atoms to chemical change
Sample Questions 3. Individual atoms are observable with a. the naked eye b. a magnifying glass c. a light microscope d. a scanning tunneling microscope
Pair-Share-Respond 1. Whatisanatom?2. WhatdidDemocritusbelieve?3. ListthefourpartsofDalton’satomictheory.
Chemistry Day 8 Thursday, September 19th – Friday,
September 20th, 2019
Do-Now Title: “BrainPOP: Atoms” 1. Use your periodic table to complete the do-
now (questions 1-10) on the worksheet provided. Do not turn over until instructed to do so.
Finished? Take out your planner and table of
contents.
BrainPOP:Atoms
• WatchtheBrainPOPvideo• Wewillcompleteashortactivityinourgroupsafterwards
https://www.brainpop.com/science/matterandchemistry/atoms/
FLT • I will be able to describe early atomic
models by completing Early Atomic Theory Notes B
Standard HS-PS1-8:Developmodelstoillustratethechangesinthecompositionofthenucleusoftheatomandtheenergyreleasedduringtheprocessesoffission,fusion,andradioactivedecay
Structure of the Atom
What is an atom made of? • As it turns out, atoms ARE divisible, as three
main subatomic particles were discovered: § Protons
§ Abbreviation: p+
§ Neutrons § Abbreviation: n0
§ Electrons § Abbreviation: e-
Subatomic Particles • Protons = • Charge: +1 charge • Location: particles found in the nucleus of an
atom • Mass: Relative mass = 1
Subatomic Particles • Neutrons = • Charge: uncharged • Location: particles found in the nucleus of an
atom • Mass: Relative mass = 1
Subatomic Particles • Electrons = • Charge: -1 charge • Location: particles found orbiting around the
nucleus • Mass: Insignificant mass
How???? • If atoms were so difficult to discover given their
tiny size, how were subatomic particles discovered??
What does this mean? • What do we know about the two ends of
magnets? • What happens when we push magnets close
together (two different things can happen)? Why?
The discovery of the electron... • In 1897, J.J. Thomson discovered the electron • He conducted experiments using electric currents
passing through gases at low pressure
The discovery of the electron... • These electric currents produced a cathode
ray (a glowing beam) that traveled from the cathode (-) to the anode (+)
What does this look like?
In summary • Because the movement of the stream was from
the cathode (negative end) to the anode (positive end), there must be some part of the atom that is NEGATIVELY charged
Protons & Neutrons • 1886: Goldstein performed a similar experiment
and observed that there were positively-charged particles traveling toward the cathode. These positive particles would later be called protons.
Protons & Neutrons • 1932: Chadwick
discovered the neutron. This particle was hard to discover because it is neutral, but it has a significant mass (about equal to a proton) that Chadwick studied.
Our Particles
Okay, so there are three particles... • How did scientists figure out the atom’s
composition?
Developing Atomic Theory… • Dalton thought atoms were
simply indivisible spheres • plum pudding model: J. J.
Thomson thought there were just (-)-charged particles scattered within a (+)-charged sphere
• But then someone else discovered the nucleus...
Ernest Rutherford • In 1911, Rutherford’s
experiments involved shooting a beam of POSITIVELY CHARGED alpha particles at a thin sheet of gold foil
• He noticed that the vast majority of alpha particles passed through the foil easily.
• However, there were a FEW particles that were DEFLECTED back (did not go through).
• Theonesthathitdeadcenterwerecompletelyreflected
Rutherford’s Conclusions • Most of the particles passed
through --> Most of an atom is empty space
• A few (very few) particles were deflected back --> since the alpha particles are positive, there must be a tiny, dense, positively-charged center in an atom
Our atomic model so far... • Atoms are composed of three main subatomic
particles: p+, n0, e- • Protons and neutrons are located in the
nucleus of the atom, which is a very small, but dense (contains a LOT of mass in a small volume)
• Electrons are VERY tiny, negatively charged, and orbit around the nucleus. They make up most of the VOLUME of the atom. – Electronsdeterminethepropertiesofouratoms
But of course... • ...we still haven’t talked about modern atomic
theory and models yet :)
Sample Questions 1. Which of the following is NOT an example of a
subatomic particle? a. proton b. molecule c. electron d. neutron
Sample Questions 2. The nucleus of an atom consists of a. electrons only b. protons only c. protons and neutrons d. protons and electrons
Sample Questions 3. Most of the volume of the atom is occupied by
the a. electrons b. protons c. protons and neutrons d. neutrons
Sample Questions 4. Which scientist discovered the neutron? a. Chadwick b. Dalton c. Thomson d. Rutherford
Pair-Share-Respond 1. Identifyourthreesubatomicparticles–listtheircharge,mass,andlocation.
2. DescribeThomson’splumpuddingmodel
3. ExplainwhatwasmissingfromThomson’splumpuddingmodel
4. WhatwereRutherford’stwoconclusions?