chemistry week 5 · nuclear stability • larger nuclides tend to be more unstable – all nuclides...

Chemistry Monday, September 25th – Tuesday,

September 26th, 2017

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.

Announcements •  ToCmustbeturnedinbyFriday•  Recall

– TobeexemptfromsemesterfinalyoucannotmissmorethanfourTOTALstampsfromourToC’s

– Youalsoneeda70%+onunittestsandnomissinglabs/quizzes

•  Retakeoldquizzesandtrade-indojopoints

•  BacktoschoolnightThursday• MinimumdayFriday

Planner: •  Last day for stamps: Thursday •  ToC due by Friday (turn in to HW box) •  Read Ch. 19 (all) •  Retake Ch. 3 Quiz Table of Contents #1:

24. Nuclear Notation Review 25. Ch. 19 CN Part A

Review

CW 1. Take 10-15 minutes to complete the

review WS in your groups –  Mass number for Br is 80, and the mass

number for Pb is 212

2. When finished, start reading Ch. 19

3. We will begin our notes shortly

FLT •  I will be able to describe the three main

types of nuclear radiation by completing Ch. 19 CN A

Standard HS-PS1-8:Developmodelstoillustratethechangesinthecomposi;onofthenucleusoftheatomandtheenergyreleasedduringtheprocessesoffission,fusion,andradioac;vedecay

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?• Whatarethethreetypesofradioac;vedecay?

• Whichisthedeadliesttypeofradioac;vedecay?

• HowdoyouprotectyourselffromAlpharadia;on?

Review–AtomicModels

Nucleons and Nuclear Forces

SubatomicPar;cles•  In1932,JamesChadwickdiscoveredtheneutron

•  Thiswasimportantinimprovingtheproton-electronatomicmodel

•  Newmodel:Theproton-neutronnucleus

Proton-NeutronModel

SubatomicPar;cles•  Wenowhavethreesubatomicpar;cles:– Protonsp+– Electronse-– Neutronsn0

•  Nucleons=subatomicparNcleslocatedinthenucleusofatoms(p+andn0)– Nucleonsarecomposedofsmallerpar;clescalledquarks

Forces•  Therearetwomainforcesatplayinournucleus:

–  Electromagne;cforce(proton-protonrepulsion)–  Strongforce(nucleonss;cktogether)

Forces•  Notallnucleiarestable

–  Posi;vely-chargedprotonscanrepeleachother•  StrongNuclearForce=bindsp+andn0togetherinthenucleus

Unstable Nuclei – Strongforce=holdsnucleitogetherovershortdistances

– Largernucleicanbemoreunstable

Nuclear Stability

NuclearStability•  StrongNuclearForce

– Thisforcecanonlyactoververyshortdistances– ItisthestrongestaXrac;veforce(137;mesmorethanelectromagne;c)

– Overextremelyshortdistances,thestrongnuclearforceoverridestherepulsionoftheelectromagne;cforce

•  Lookingatthera;oofprotonstoneutronscanhelpusdeterminethestabilityofthenucleus

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),aswellasradioac;veelements

•  Curiestudiedmaterialsthatgaveoffrays,whichshecalledradioac;vity

Radiation •  Radia;on=Rays∥clesemiXedbyaradioac;vesource

Radiation Radioisotopes=unstableisotopeswhosenucleiundergochangestobecomemorestable

Radioactivity

– Anunstablenucleus“decays”intoanewnucleusbychangingitsnumberofprotonsspontaneously

– Ifthenumberofprotonschanges,isitthesameelementanymore?

Radioactivity – RadioacNvedecay=unstablenucleusreleasesenergy/emitsradiaNon

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

•  AlphaparNclesaretheleastpenetraNng.GammaraysarethemostpenetraNng.

Figure4.2:Thepenetra;ngpowerofradia;on.

© 2003 John Wiley and Sons Publishers

Arethereothertypesofdecay?

α-par;cleproduc;on

Spontaneousfission

β-par;cleproduc;on

Positronproduc;on

γ-rayproduc;on

Positron Production

•  Positron = positively charged anti-electron

Review 1. Certain elements are radioactive because their atoms have

a.  more neutrons than electrons. b.  an unstable nucleus. c.  a large nucleus. d.  more neutrons than protons.

Review 2. An unstable nucleus releases energy by

a.  emitting radiation. b.  thermal vibrations. c.  a chemical reaction. d.  giving off heat.

Review 3. Which property does NOT describe an alpha particle?

a.  2+ charge b.  a relatively large mass c.  a negative charge d.  low penetrating power

Review

4. When a radioactive nucleus releases a high-speed electron, the process can be described as

a.  oxidation. b.  alpha emission. c.  beta emission. d.  gamma radiation.

Pair-Share-Respond 1. Whatareradioisotopes?2. Whatareourthreemaintypesof

radia;on?3. Whichtypeisthemostdangerous?4. WhatisemiXedinbetadecay?5. WhatisemiXedinalphadecay?

CW 1. Underneath your notes, complete

the questions from page 694: –  #1-5, 8, 9, 11

2. Finished? Read Ch. 19 Carefully

Chemistry Wednesday, September 27th – Thursday,

September 28th, 2017

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.

Announcements •  ToCdue•  Finishretakes•  AYendtutoringasneeded• Musthavecalculatorsnextweek

•  Unittest– MulNplechoicesecNonandresponsesecNon

Planner: •  Turn in ToC •  Study for Unit Test (Ch. 1, 3, 13, 19) •  Bring calculators next week Table of Contents #2:

1.  Video Notes: Nuclear Processes

Video Notes • Let’sreviewsomeoftheconceptswecovered,aswellaslookatsometopicswewillbecoveringsoon

Video Notes 1.  Whatarethefourfundamental

forces?2.  Dis;nguishbetweennuclearfusion

andfission.3.  Anatomicbombuseswhichof

theseprocesses?4.  Whyisradioac;vedecayusefulto

uswhenstudyinghistory?5.  Oneaddi;onalfact

Video Notes 1.  Whatarethefourfundamental

forces?2.  Dis;nguishbetweennuclearfusion

andfission.3.  Anatomicbombuseswhichof

theseprocesses?4.  Whyisradioac;vedecayusefulto

uswhenstudyinghistory?5.  Oneaddi;onalfact

Introduction to Half-Life

Introduction to Half-Life • Unstablenucleidecay• Dotheyalldecayatthesamerate?

Introduction to Half-Life • Thehalf-lifeofanuclideistheNmeittakesfor½ofthesampletodecay

• A^ereachhalf-life,halfoftheremainingatomshavedecayed

intoanewelement

• Wecanrepresentthisgraphically– Whatwouldthatlooklike?

Introduction to Half-Life

Mini-Lab

Ch 19 Radioactive Half-Life Lab • Youwillusem&m’sorskiXlestorepresentisotopes– Whatareisotopes?

• Youmustplacepapertowelsoveryoursta;on/table– Pleasedonoteatwhileperformingthelab

– Contaminatedcandiesshouldbethrownoutattheend

– Tablesmustbewipeddownattheendforsanita;onpurposes

Ch 19 Radioactive Half-Life Lab • WriteyourstarNngnumberofcandies

– Youwillneedtocountout100candieswithoutcontaminaNon

• Usetwocupstoshakeyourcandies

• Pourthemoutacrossthepapertowels

Ch 19 Radioactive Half-Life Lab • Candiesfacingup=remainingisotopesàkeeptheseforthenextround

– Recordtheremainingnumberin

yourdatatable

• Candiesfacingdown=decayedisotopesàsettheseaside,astheywillnotbeusedanymore

Ch 19 Radioactive Half-Life Lab • Gatherupyourremainingcandiesandshakethemup.RepeatthestepsunNlallisotopeshave“Decayed”.

Time Classdata

1millionyears

2millionyears

3millionyears

4millionyears

5millionyears

6millionyears

7millionyears

8millionyears

9millionyears

10millionyears

11millionyears

12millionyears

Ch 19 Radioactive Half-Life Lab • Graphyourresultsonthebackofthepage.Don’tforgettolabelyouraxes.

• Alsographtheclassaveragedatausingadifferentcolorpen.

– Youshouldlabeleachorhaveakey• UsetheclassaveragegraphtoanswerthequesNonsbelow.

CW • TurninlabswhenfinishedJ

– Didyouanswerincompletesentences?

• StudyCh.19– Testnextweek!

• TurninToCifit’sready

Chemistry Friday, September 29th – Monday, October

2nd, 2017

Planner: •  Finish WS + Study for Ch. 19 Quiz • Unit Test (Ch. 1, 3, 13, 19) 10/9-10/10 • Next lesson: calculators Table of Contents #2:

2.  Return of the Brainstorm 3.  Ch. 19 CN B 4.  Nuclear Radiation WS

Announcements •  Classdojoadjustment:

– 5points:pen,pencil,snack(limitoneperday)– 10points:newreferencesheet– 15points:stamp

•  Unittest– Tues/Wed

• FinishCh.19– Thurs/Fri

• Ch.19Quiz+UnitReview– Mon/Tues

• UnitTest

Announcements •  AnoteontheToC

– ToC’swithallstamps=+5dojopoints

– Missingstampsaretotaledattheendofeachsemestertohelpdeterminewhoisexemptfromthefinalornot

– Unstampedassignmentscanbeturnedinwithan“Incompleteassignment”formwiththeToCforparNalcreditàstapleeverythingtogether

FLT •  I will be able to write balanced nuclear

equations by completing Ch. 19 Notes B

Standard HS-PS1-8:Developmodelstoillustratethechangesinthecomposi;onofthenucleusoftheatomandtheenergyreleasedduringtheprocessesoffission,fusion,andradioac;vedecay

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

Ch. 19 CN B: Nuclear Transformation

Guiding Questions • What is nuclear fusion? • What is nuclear fission? • How do we write and balance

nuclear equations?

Recall

Radiation •  When a nucleus spontaneously breaks down by

emitting radiation, the process is called radioactive decay.

Alpha Emission •  Emits alpha particles, which contain two protons

and two neutrons and has a double positive charge.

•  Alpha emitters are radioisotopes that decay by emitting alpha particles

αpar;cle=4He

2

Beta Emission •  Emit beta particles •  The neutron breaks apart into a proton, which

remains in the nucleus, and a fast-moving electron, which is released. This increases the atomic number by one.

β-par;cle=0e-1

Gamma Emission •  Nuclei often emit gamma rays along with alpha

or beta particles during radioactive decay.

Nuclear Equations

Nuclear Equations •  Radioactive decay can be shown in a nuclear

equation using the symbols for the original radioactive nucleus, the new nucleus, and the radiation emitted.

•  Nuclear Equations à Balanced when both sides are equal to each other

•  Radioactive nucleus à new nucleus + radiation

Nuclear Equations •  In nuclear reactions, atoms transmutate •  Transmutation = Conversion of an atom of

one element into an atom of another element

•  Transmutation can occur by radioactive decay or when bombarded by other particles

CopyThisExample:

BALANCINGNUCLEAREQUATIONS1. Sumofmassnumbersmustbe=oneachside(le^

superscripts)

2. Sumsofatomicnumbers/charges(le^subscripts)oneachsideoftheequaNonmustbe=.

Examples:238U 4He+234Th92 290

214Pb 0β + 214Bi82 -183

Trythese:

CompletethenuclearequaNonsandstatethetypeofdecay:

1.217At213Bi+?

2.231Th0β+?

-1

3.208Tl 0e+?

-1

85 83

4He2

90231Pa91

208Pb8281

Fission & Fusion

Nuclear Fission •  When the nuclei of certain isotopes are

bombarded with neutrons, they undergo fission •  Fission = the splitting of a nucleus into

smaller fragments/nuclei.

Nuclear Fission •  Chain reaction = Fission produces neutrons,

causing other atoms to undergo fissions, which in turn releases more neutrons, etc.

Nuclear Fusion •  The energy released by the sun results from

nuclear fusion. •  Fusion = when nuclei combine to produce a

nucleus of greater mass.

Nuclear Fusion •  Fusion reactions, in which small nuclei combine,

release much more energy than fission reactions, in which large nuclei split.

Pair-Share-Respond 1. What is a transmutation?2. Distinguish between nuclear fission and

nuclear fusion.3. Which type releases more energy?

4. Complete the balanced equation:

Reminderfortoday’sWS

α-par;cleproduc;on

Spontaneousfission

β-par;cleproduc;on

Positronproduc;on

γ-rayproduc;on

FYI:ElectronCapturevs.BetaDecay

CW • Complete the WS

– Use periodic table – If written in isotope notation (example:

Carbon-14 or C-14) change to shorthand notation first

– Study by reading notes, the textbook, or quizzing your group members