Chemistry Day 10 - Weebly

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%


1.11%


<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.

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

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

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