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Chapter 6: The Periodic Table
Chapter summary6:1 History od the Periodic table
1) Mendeleev’s Periodic table2) Problems with early periodic
tables
6:2 Modern Periodic table1) Key points: Periodic law, Periods
and Groups, 3 broad classes of elements2) Properties of the 3
classes of elements (Metals, nonmetals and metalloids)3) Sorting
elements based on general properties (3-types)4) Sorting elements
based on electron configuration (4-types)5) Periodic trends:
a) Atomic sizeb) Ionization energyc) Ionic sized)
Electronegativity Chemistry _ Notes
Dr. Chirie Sumanasekera10 /30/ 201711/7/2017
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4.Sortingelementsbasedonelectronconfiguration(highestenergyorbitalsfilled)
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5.PeriodicTrends
1. Ionization energy
2. Electronegativity
3. Atomic size (Atomic radius)
4. Ionic size (Ionic radius)
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Cation(+ion)=anatomthathaslostoneormoreelectrons(morePthanelectrons)
Anion(-
ion)=anatomthathasgainedoneormoreelectrons(lessPthanelectrons)
Ionizationenergy=theenergyrequiredtoremoveanelectron(“cationizationenergy”)
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Ionizationenergy(andElectronegativity)=increasesacrossaperiodandupagroup
Atomicnumber
Ionizatio
nen
ergy(K
J/mol)
1. FirstIonizationenergy
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Li
Na
KRb
Cs
HeNe
KrAr
Xe
Atomicnumber
Radius(p
m)
2. AtomicRadii(radiusofAtoms=Atomicsize)
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3. AtomicRadii(radiusofAtoms=Atomicsize)
•
Increaseasyougodownagroup(electronsfillmoreandmorehigherenergylevelsasyoumovedown–
sotheradiusincreases)
•
Decreaseasyougoacrossaperiod(innershellelectronsremainthesamebutProtonnumberincreases.Shielding=outershellelectronsbytheinnershellelectronsfromtheattractionofthenucleus
ChemistryNotesfor11-9-17
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ComparisonofionicRadii(radiusofanion)
IONICSIZE:Whenaneutralatomlosesanelectronitsradiusbecomessmaller(Ex:LiatomislargerthanLi+cationthathaslostanelectron)Whenaneutralatomsgainanelectronitsradiusbecomeslarger(Ex:ClatomsmallerthanCl-
anion.ThisisbecauseCl-
hasmoreelectronsthanprotonssotheouter-shellelectronsarepulledinlessthantheyareintheClatom).
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4.Electronegativity(electronaffinity)=Howbadlydoesanatominamolecule
wanttohog/pull electrons
• Fluorine(F) is the
mostelectronegativeelementontheperiodictable.FollowedbyO,thenNandCl.
•
Ingeneraltheelectronegativityofanelementincreasesasonegoesupafamily.Electronegativityincreasesintheorder:I<Br<Cl<F.
• Also,electronegativityincreases
asonegoesacrossthetable.Electronegativityincreasesintheorder:B<C<N<O<F.
e- e-
ATOMA(WeakPull)
ATOMBStrongpull
Bigelectronegativitydifference
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Summary
Eelectronegativity
Eelectrone
gativ
ity
