Chemistry Day 10 Monday, September 17th – Tuesday,
September 18th, 2018
Do-Now Title: “Brainstorm: Unit 1” 1. Write down today’s FLT 2. Draw what an atom looks like according to
Democritus and Dalton 3. Draw what an atom looks like according to J.J.
Thomson 4. Draw what an atom looks like according to Ernest
Rutherford 5. Use one of the pro-talk sentence frames to tell me
something we have learned about atoms or subatomic particles.
6. Underneath your do-now, write “Brainstorm list” and number 1-20
Finished? Take out your planner and table of contents.
Brainstorm Protocol 1. Thegoalistogeneratethelongestpossiblelist
asagroup2. Whenpromptedtodoso,identifywhowill
providethefirstanswer3. Then,goclockwisetothenextperson.4. Donotskippeopleanddonotsayananswer
forthem.5. OnlysayONEansweratatime6. Quantityoverquality7. Stayontopic8. PencilsmustbedownwhenIsaytimeisup9. Listsmustbeexactlythesame
FLT • I will be able to calculate the mass
number and average atomic mass in an atom by completing Atoms CN
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
Distinguishing Among Atoms
Guiding Questions • Whatmakeselementsandisotopesdifferent?• Howcanwecalculatethenumberofneutronsinanatom?
• HowcanIcalculatetheatomicmassofanelement?
• CanIexplainwhychemistsusetheperiodictable?
Recall • Atoms of the same element are identical • Atomsarecomposedofidenticalprotons,neutrons,andelectrons
Recall • An atom’s atomic number (Z) = the # of
protons in the nucleus. Defines element.
Recall • Elementsaredifferentbecausetheycontaindifferentnumbersofprotonsàifyouchangethenumberofprotons,youchangetheelement
Recall • Atoms are
electrically neutral • Protonshavea+1charge
• Whatbalancesthem?• Electronshavea-1charge
• Therefore,#protons=#electronsinanatom
Groups have similar properties
Mass Number • Recall:
– Protonshavearelativemassof1
– Neutronshavearelativemassof1
– Electronshavearelativelyinsignificantmass
Mass Number • Therefore…
– Mass#=p++n0
Nuclide p+ n0 e- Mass #
Oxygen -
10
- 33 42
- 31 15
Shorthand Notation MassNumber
AtomicNumber
Symbol
Shorthand Notation ■ Find each of these:
a) number of protons
b) number of neutrons
c) number of electronsd) Atomic number
e) Mass Number C 14
6
Shorthand Notation ■ If an element has an atomic number of
34 and a mass number of 78, what is the: a) number of protonsb) number of neutrons
c) number of electronsd) shorthand notation
Shorthand Notation ■ If an element has 91 protons and
140 neutrons what is the a) Atomic numberb) Mass number
c) number of electronsd) shorthand notation
Shorthand Notation ■ If an element has 78 electrons and
117 neutrons what is the a) Atomic numberb) Mass number
c) number of protonsd) shorthand notation
Isotopes • What was Dalton mistaken about? • Dalton was also wrong about all elements of
the same type being identical
Isotopes • Atoms of the same element can have
different numbers of neutrons.• Thus, different mass numbers.• These are called isotopes.
Isotopes • FrederickSoddy(1877-1956)proposedtheideaofisotopesin1912
• Isotopes=atomsofthesameelementhavingdifferentmasses,duetovaryingnumbersofneutrons.
• SoddywontheNobelPrizeinChemistryin1921forhisworkwithisotopesandradioactivematerials.
Isotopes
• We can also put the mass number after the name of the element: – carbon-12 – carbon-14 – uranium-235
Isotopes Isotope Protons Electrons Neutrons Nucleus
Hydrogen–1
(protium)
1
1
0
Hydrogen-2
(deuterium)
1
1
1
Hydrogen-3
(tritium)
1
1
2
Isotopes
• Elements occur in nature as mixtures of isotopes.
Atomic Mass § Howheavyisanatomofoxygen?§ Itdepends,becausetherearedifferentkindsofoxygenatoms.
§ Wearemoreconcernedwiththeaverageatomicmass.
§ Averageatomicmass=weightedaverageoftheisotopesofagivenelementbasedontheabundance(%)innature
Atomic Mass • Each isotope has its own atomic
mass, thus we determine the average from percent abundance.
Calculating Atomic Mass • Multiply the atomic mass of
each isotope by it’s abundance (expressed as a decimal), then add the results.
• If not told otherwise, the mass of the isotope is expressed in atomic mass units (amu)
Atomic Masses
Isotope Symbol Composition of the nucleus
% in nature
Carbon-12 12C 6 protons 6 neutrons
98.89%
Carbon-13 13C 6 protons 7 neutrons
1.11%
Carbon-14 14C 6 protons 8 neutrons
<0.01%
Atomic mass is the average of all the naturally occurring isotopes of that element.
Carbon = 12.011
Pair-Share-Respond 1. What is Z? 2. Can atoms of the same element have
different numbers of protons? 3. Discuss all information you can
derive from the shorthand notation pictured
4. Explain how isotopes differ from one another.
5. What is meant by the term “average atomic mass”?
Chemistry Day 11 Wednesday, September 19th – Thursday,
September 20th, 2018
Do-Now Title: “Nuclear Notation Review” 1. Answer the do-now questions on your
worksheet
2. Do not begin working on the other questions until instructed to do so
Finished? Take out your planner and table of
contents.
FLT • I will be able to describe the three main
types of nuclear radiation by completing Ch. 19 CN A
Standard HS-PS1-8:Developmodelstoillustratethechangesinthecompositionofthenucleusoftheatomandtheenergyreleasedduringtheprocessesoffission,fusion,andradioactivedecay
Ch. 19 Part A: Radiation • 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
Ch. 19 Part A: Radiation
Guiding Questions • Whatarethetwonuclearforces?• Whatarethethreetypesofradioactivedecay?
• Whichisthedeadliesttypeofradioactivedecay?
• HowdoyouprotectyourselffromAlpharadiation?
Review–AtomicModels
Nucleons and Nuclear Forces
SubatomicParticles• In1932,JamesChadwickdiscoveredtheneutron
• Thiswasimportantinimprovingtheproton-electronatomicmodel
• Newmodel:Theproton-neutronnucleus
Proton-NeutronModel
SubatomicParticles• Wenowhavethreesubatomicparticles:– Protonsp+– Electronse-– Neutronsn0
• Nucleons=subatomicparticleslocatedinthenucleusofatoms(p+andn0)– Nucleonsarecomposedofsmallerparticlescalledquarks
Forces• Therearetwomainforcesatplayinournucleus:
– Electromagneticforce(proton-protonrepulsion)– Strongforce(nucleonssticktogether)
Forces• Notallnucleiarestable
– Positively-chargedprotonscanrepeleachother• StrongNuclearForce=bindsp+andn0togetherinthenucleus
Unstable Nuclei – Strongforce=holdsnucleitogetherovershortdistances
– Largernucleicanbemoreunstable
Nuclear Stability
NuclearStability• StrongNuclearForce
– Thisforcecanonlyactoververyshortdistances– Itisthestrongestattractiveforce(137timesmorethanelectromagnetic)
– Overextremelyshortdistances,thestrongnuclearforceoverridestherepulsionoftheelectromagneticforce
• Lookingattheratioofprotonstoneutronscanhelpusdeterminethestabilityofthenucleus
Band of Stability
• The region on a graph which indicates all stable nuclei when the number of neutrons are compared to the number of protons for all stable nuclei
NuclearStability• Largernuclidestendtobemoreunstable
– Allnuclideswithmorethan83protons(bismuth)areunstable
• Mostnuclideswanta1:1ofneutrons:protons– Heaviernuclidesneedmoreneutrons
Pair-Share-Respond 1. What are nucleons? 2. What force holds nucleons together? 3. What types of nuclei tend to be
unstable?
Radioactivity
Radioactivity
• Howdoesanunstablenucleusreleaseenergy?
Context • MarieCurie(1867-1934)helpeddiscovernewelements(PoloniumandRadium),aswellasradioactiveelements
• Curiestudiedmaterialsthatgaveoffrays,whichshecalledradioactivity
Radiation • Radiation=Rays&particlesemittedbyaradioactivesource
Radiation Radioisotopes=unstableisotopeswhosenucleiundergochangestobecomemorestable
Radioactivity
– Anunstablenucleus“decays”intoanewnucleusbychangingitsnumberofprotonsspontaneously
– Ifthenumberofprotonschanges,isitthesameelementanymore?
Radioactivity – Radioactivedecay=unstablenucleusreleasesenergy/emitsradiation
Types of Radiation
Types of Radiation
What are the three main types of nuclear radiation?
Main Types of Radiation
1. Alpha (α) Radiation 2. Beta (β) Radiation 3. Gamma (Υ) Radiation
Alpha Radiation Alpha radiation = Emits alpha particles (helium) • Mass number decreases by 4, atomic number
decreases by 2
Alpha Radiation Ex/
Beta Radiation
• Beta Radiation = Emits a beta particle (electron) – Mass number stays the same. Atomic number increases by
1.
Beta Radiation Ex/
Gamma Radiation
• Gamma radiation = Emits a high-E photon(gamma ray).
• Tends to accompany other nuclear decay processes
Types of Radiation
• Alphaparticlesaretheleastpenetrating.Gammaraysarethemostpenetrating.
Figure4.2:Thepenetratingpowerofradiation.
© 2003 John Wiley and Sons Publishers
Arethereothertypesofdecay?
α-particleproduction
Spontaneousfission
β-particleproduction
Positronproduction
γ-rayproduction
Positron Production
• Positron = positively charged anti-electron
Pair-Share-Respond 1. Whatareradioisotopes?2. Whatareourthreemaintypesof
radiation?3. Whichtypeisthemostdangerous?4. Whatisemittedinbetadecay?5. Whatisemittedinalphadecay?
CW 1. Underneath your notes, complete
the questions from page 601: – 19.1 Questions #1, 3-7, 9-10, 12-20
2. Finished? Read Ch. 19 Carefully
Chemistry Day 12 Friday, September 21st – Monday,
September 22nd, 2018
Do-Now Title: “Video Notes: Nuclear Processes” 1. Write down today’s FLT. 2. When can you retake quizzes? 3. What can you trade in your dojo points for? List
specific examples with how many points they cost 4. Why do some nuclei undergo decay? 5. Identify the three main types of decay, and list
them in order from least penetrating to most penetrating
6. Use a pro-talk sentence frame to make a claim about nuclei, radiation, or decay.
7. Write “Video Notes” underneath your do-now Finished? Take out your planner and table of
contents.
Video Notes • Let’sreviewsomeoftheconceptswecovered,aswellaslookatsometopicswewillbecoveringsoon
Video Notes 1. Whatarethefourfundamental
forces?2. Distinguishbetweennuclearfusion
andfission.3. Anatomicbombuseswhichof
theseprocesses?4. Whyisradioactivedecayusefulto
uswhenstudyinghistory?5. Oneadditionalfact
Video Notes 1. Whatarethefourfundamental
forces?2. Distinguishbetweennuclearfusion
andfission.3. Anatomicbombuseswhichof
theseprocesses?4. Whyisradioactivedecayusefulto
uswhenstudyinghistory?5. Oneadditionalfact
Introduction to Half-Life
Introduction to Half-Life • Unstablenucleidecay• Dotheyalldecayatthesamerate?
Introduction to Half-Life • Thehalf-lifeofanuclideisthetimeittakesfor½ofthesampletodecay
• Aftereachhalf-life,halfoftheremainingatomshavedecayedintoanewelement
• Wecanrepresentthisgraphically– Whatwouldthatlooklike?
Introduction to Half-Life
Mini-Lab
Time Classdata
1millionyears
2millionyears
3millionyears
4millionyears
5millionyears
6millionyears
7millionyears
8millionyears
9millionyears
10millionyears
11millionyears
12millionyears