dr. s. m. condren chapter 8 atomic electron configurations and chemical periodicity

Dr. S. M. Condren

Chapter 8

Atomic Electron Configurations

and Chemical Periodicity

Dr. S. M. Condren

ATOMIC ELECTRON ATOMIC ELECTRON CONFIGURATIONS AND CONFIGURATIONS AND

PERIODICITYPERIODICITY

ATOMIC ELECTRON ATOMIC ELECTRON CONFIGURATIONS AND CONFIGURATIONS AND

PERIODICITYPERIODICITY

Dr. S. M. Condren

Atomic Orbitals

• Types of orbitals found in the known elements: s, p, d, and f

• schools play defensive football

• Packer version: secondary pass defense fails

Dr. S. M. Condren

Atomic Orbitals

Shapes

• s – spherical

• p – dumbbell

• d – complex

• f – very complex

Dr. S. M. Condren

Arrangement of Electrons in AtomsArrangement of Electrons in AtomsArrangement of Electrons in AtomsArrangement of Electrons in Atoms

Electrons in atoms are arranged asElectrons in atoms are arranged as

SUBSHELLS (l)SUBSHELLS (l)

ORBITALS (mORBITALS (mll))

SHELLS (n)SHELLS (n)

Dr. S. M. Condren

Each orbital can be assigned no Each orbital can be assigned no

more than 2 electrons!more than 2 electrons!

This is tied to the existence of a 4th This is tied to the existence of a 4th

quantum number, the quantum number, the electron electron

spin quantum number, mspin quantum number, mss..

Arrangement of Electrons in AtomsArrangement of Electrons in AtomsArrangement of Electrons in AtomsArrangement of Electrons in Atoms

Dr. S. M. Condren

Electron Electron Spin Spin

Quantum Quantum Number, Number,

mmss

Can be proved experimentally that electronCan be proved experimentally that electronhas a spin. Two spin directions are given byhas a spin. Two spin directions are given bymmss where m where mss = +1/2 and -1/2. = +1/2 and -1/2.

Can be proved experimentally that electronCan be proved experimentally that electronhas a spin. Two spin directions are given byhas a spin. Two spin directions are given bymmss where m where mss = +1/2 and -1/2. = +1/2 and -1/2.

Dr. S. M. Condren

Electron Spin and MagnetismElectron Spin and Magnetism•DiamagneticDiamagnetic: NOT : NOT

attracted to a magnetic attracted to a magnetic

fieldfield

•ParamagneticParamagnetic: :

substance is attracted to substance is attracted to

a magnetic field. a magnetic field. •Substances with Substances with

unpaired electronsunpaired electrons are are

paramagnetic.paramagnetic.

Dr. S. M. Condren

Measuring ParamagnetismMeasuring Paramagnetism

ParamagneticParamagnetic: substance is attracted to a : substance is attracted to a magnetic field. Substance has magnetic field. Substance has unpaired electronsunpaired electrons..

DiamagneticDiamagnetic: NOT attracted to a magnetic field: NOT attracted to a magnetic field

Active Figure 8.2

Dr. S. M. Condren

n ---> shelln ---> shell 1, 2, 3, 4, ...1, 2, 3, 4, ...

l ---> subshelll ---> subshell 0, 1, 2, ... n - 10, 1, 2, ... n - 1

mmll ---> orbital ---> orbital -l ... 0 ... +l-l ... 0 ... +l

mmss ---> electron spin ---> electron spin +1/2 and -1/2+1/2 and -1/2

n ---> shelln ---> shell 1, 2, 3, 4, ...1, 2, 3, 4, ...

l ---> subshelll ---> subshell 0, 1, 2, ... n - 10, 1, 2, ... n - 1

mmll ---> orbital ---> orbital -l ... 0 ... +l-l ... 0 ... +l

mmss ---> electron spin ---> electron spin +1/2 and -1/2+1/2 and -1/2

QUANTUM NUMBERSQUANTUM NUMBERSNow there are four!Now there are four!

Dr. S. M. Condren

Pauli Exclusion PrinciplePauli Exclusion Principle

No two electrons in the same No two electrons in the same atom can have the same set atom can have the same set of 4 quantum numbers.of 4 quantum numbers.

That is, each electron has a That is, each electron has a unique address.unique address.

Dr. S. M. Condren

Electrons in AtomsElectrons in AtomsElectrons in AtomsElectrons in Atoms

When n = 1, then l = 0When n = 1, then l = 0

this shell has a single orbital (1s) to which this shell has a single orbital (1s) to which

2e- can be assigned2e- can be assigned

When n = 2, then l = 0, 1When n = 2, then l = 0, 1 2s orbital 2s orbital 2e-2e- three 2p orbitalsthree 2p orbitals 6e-6e- TOTAL = TOTAL = 8e-8e-

Dr. S. M. Condren


When n = 3, then l = 0, 1, 2When n = 3, then l = 0, 1, 2

3s orbital 3s orbital 2e-2e-

three 3p orbitalsthree 3p orbitals 6e-6e-

five 3d orbitalsfive 3d orbitals 10e-10e-

TOTAL = TOTAL = 18e-18e-

When n = 3, then l = 0, 1, 2When n = 3, then l = 0, 1, 2





Dr. S. M. Condren


When n = 4, then l = 0, 1, 2, 3When n = 4, then l = 0, 1, 2, 3




seven 4f orbitalsseven 4f orbitals 14e-14e-


And many more!And many more!And many more!And many more!

Dr. S. M. Condren

Dr. S. M. Condren

• Electrons generally assigned to Electrons generally assigned to

orbitals of successively higher orbitals of successively higher

energy.energy.

• For For H atomsH atoms, E = - C(1/n, E = - C(1/n22). E ). E

depends only on n.depends only on n.

• For For many-electron atomsmany-electron atoms, energy , energy

depends on both n and l.depends on both n and l.

• Electrons generally assigned to Electrons generally assigned to

orbitals of successively higher orbitals of successively higher

energy.energy.

• For For H atomsH atoms, E = - C(1/n, E = - C(1/n22). E ). E

depends only on n.depends only on n.

• For For many-electron atomsmany-electron atoms, energy , energy

depends on both n and l.depends on both n and l.

Assigning Electrons to AtomsAssigning Electrons to Atoms

Dr. S. M. Condren

Electron Electron Filling Filling OrderOrder

Dr. S. M. Condren

LED Traffic Lights

http://mrsec.wisc.edu/Edetc/background/LED/traffic_light/index.htm

Chapter 7, Problem 3, page 326 text

Dr. S. M. Condren

11 s

value of nvalue of l

no. ofelectrons

spdf notationfor H, atomic number = 1

Two ways of Two ways of writing configs. writing configs. One is called the One is called the spdf notation.spdf notation.

Writing Atomic Electron ConfigurationsWriting Atomic Electron Configurations

Dr. S. M. Condren

Arrowsdepictelectronspin

ORBITAL BOX NOTATIONfor He, atomic number = 2

1s

21 s

Arrowsdepictelectronspin

ORBITAL BOX NOTATIONfor He, atomic number = 2

1s

21 s

One electron has n = 1, l = 0, mOne electron has n = 1, l = 0, m ll = 0, m = 0, mss = + 1/2 = + 1/2

Other electron has n = 1, l = 0, mOther electron has n = 1, l = 0, m ll = 0, m = 0, mss = - 1/2 = - 1/2

Writing Atomic Electron ConfigurationsWriting Atomic Electron Configurations

Other is called the Other is called the orbital box notationorbital box notation

Dr. S. M. CondrenSee “Toolbox” on CD for Electron Configuration tool.See “Toolbox” on CD for Electron Configuration tool.

Dr. S. M. Condren

Electron Configurations Electron Configurations and the Periodic Tableand the Periodic Table

Dr. S. M. Condren

Group 1AGroup 1A

Atomic number = 3Atomic number = 3

1s1s222s2s11 ---> --->

3 total electrons3 total electrons

1s

2s

3s3p

2p

LithiumLithium

Dr. S. M. Condren

Group 2AGroup 2A


1s1s222s2s22 ---> --->


1s

2s

3s3p

2p

BerylliumBeryllium

Dr. S. M. Condren

Group 3AGroup 3A


1s1s2 2 2s2s2 2 2p2p11 ---> --->


1s

2s

3s3p

2p

BoronBoron

Dr. S. M. Condren

Group 4AGroup 4A


1s1s2 2 2s2s2 2 2p2p22 ---> --->

6 total electrons6 total electronsHere we see for the first time Here we see for the first time

HUND’S RULEHUND’S RULE. When . When placing electrons in a set of placing electrons in a set of orbitals having the same orbitals having the same energy, we place them singly energy, we place them singly as long as possible.as long as possible.1s

2s

3s3p

2p

CarbonCarbon

Dr. S. M. Condren

Group 5AGroup 5A


1s1s2 2 2s2s2 2 2p2p33 ---> --->


1s

2s

3s3p

2p

NitrogenNitrogen

Dr. S. M. Condren

Group 6AGroup 6A


1s1s2 2 2s2s2 2 2p2p44 ---> --->


1s

2s

3s3p

2p

OxygenOxygen

Dr. S. M. Condren

Group 7AGroup 7A


1s1s2 2 2s2s2 2 2p2p55 ---> --->


1s

2s

3s3p

2p

FluorineFluorine

Dr. S. M. Condren

Group 8AGroup 8A


1s1s2 2 2s2s2 2 2p2p66 ---> --->


1s

2s

3s3p

2p

Note that we Note that we have reached the have reached the end of the 2nd end of the 2nd period, and the period, and the 2nd shell is full!2nd shell is full!

NeonNeon

Dr. S. M. Condren

Group 1AGroup 1A


1s1s2 2 2s2s2 2 2p2p6 6 3s3s11 or or

“ “neon core” + 3sneon core” + 3s11

[Ne] 3s[Ne] 3s1 1 (uses rare gas notation)(uses rare gas notation)

Note that we have begun a new period.Note that we have begun a new period.

All Group 1A elements have [core]nsAll Group 1A elements have [core]ns11 configurations.configurations.

SodiumSodium

Dr. S. M. Condren

Group 3AGroup 3A


1s1s2 2 2s2s2 2 2p2p6 6 3s3s2 2 3p3p11

[Ne] 3s[Ne] 3s2 2 3p3p11

All Group 3A All Group 3A elements have [core] elements have [core] nsns2 2 npnp1 1 configurations configurations where n is the period where n is the period number.number.

1s

2s

3s3p

2p

AluminumAluminum

Dr. S. M. Condren

All Group 5A All Group 5A elements have elements have [core ] ns[core ] ns2 2 npnp3 3

configurations configurations where n is the where n is the period number.period number.

Group 5AGroup 5A


1s1s2 2 2s2s2 2 2p2p6 6 3s3s2 2 3p3p33

[Ne] 3s[Ne] 3s2 2 3p3p33

1s

2s

3s3p

2p

Yellow P

Red P

PhosphorusPhosphorus

Dr. S. M. Condren

Group 2AGroup 2A


1s1s2 2 2s2s2 2 2p2p6 6 3s3s2 2 3p3p66 4s 4s22

[Ar] 4s[Ar] 4s2 2

All Group 2A elements have [core]nsAll Group 2A elements have [core]ns2 2

configurations where n is the period configurations where n is the period number.number.

CalciumCalcium

Dr. S. M. Condren

All 4th period elements have the All 4th period elements have the configuration configuration [argon] ns[argon] nsxx (n - 1)d (n - 1)dyy and so are and so are d-blockd-block elements. elements.

CopperCopperIronIronChromiumChromium

Transition Metals Table 8.4Transition Metals Table 8.4

Dr. S. M. Condren

Transition Element ConfigurationsTransition Element Configurations

3d orbitals used for Sc-Zn (Table 8.4)

Dr. S. M. Condren

Dr. S. M. Condren

Board Work

• V – electron configuration

• Cr – electron configuration

• Mn – electron configuration

• Ni – electron configuration

• Cu – electron configuration

• Zn – electron configuration

Dr. S. M. Condren

Magnetism

Spins are aligned with an applied magnetic field.

Paramagnetism

Spins are randomized by thermal energy.

Ferromagnetism

Spins are aligned with or against an applied magnetic field.

Spins are ordered in magnetic domains.

Dr. S. M. Condren

NMR and MRI

800 MHz, 18.8 T NMR spectrometer Open Magnet Design MRI

http://mrsec.wisc.edu/Edetc/background/NMR/index.html

http://mrsec.wisc.edu/Edetc/cineplex/NMR/index.html

Nuclei also have spin and nuclear quantum numbers

Dr. S. M. Condren

Memory Metal

Dr. S. M. Condren

Nitinol, NiTi

http://mrsec.wisc.edu/Edetc/background/memmetal/index.html

Dr. S. M. Condren

Lanthanides and ActinidesLanthanides and ActinidesLanthanides and ActinidesLanthanides and Actinides

All these elements have the configuration All these elements have the configuration [core] [core] nsnsxx (n - 1)d (n - 1)dy y (n - 2)f(n - 2)fzz and so are and so are

f-blockf-block elements. elements.

CeriumCerium[Xe] 6s[Xe] 6s22 5d 5d11 4f 4f11

UraniumUranium[Rn] 7s[Rn] 7s22 6d 6d11 5f 5f33

Dr. S. M. Condren

Lanthanide Element ConfigurationsLanthanide Element Configurations

4f orbitals used for Ce - Lu and 5f for Th - Lr (Table 8.2)

Dr. S. M. Condren

Dr. S. M. Condren

To form cations from elements remove 1 or To form cations from elements remove 1 or more e- from subshell of highest n [or more e- from subshell of highest n [or highest (n + l)].highest (n + l)].

P [Ne] 3sP [Ne] 3s22 3p 3p33 - 3e- ---> P - 3e- ---> P3+3+ [Ne] 3s [Ne] 3s22 3p 3p00

1s

2s

3s3p

2p

1s

2s

3s3p

2p

Ion ConfigurationsIon Configurations

Dr. S. M. Condren

4s 3d 3d4s

Fe Fe2+

3d4s

Fe3+

Ion ConfigurationsIon ConfigurationsFor transition metals, remove ns electrons and For transition metals, remove ns electrons and

then (n - 1) electrons.then (n - 1) electrons.

Fe [Ar] 4sFe [Ar] 4s22 3d 3d66

loses 2 electrons ---> Feloses 2 electrons ---> Fe2+2+ [Ar] 4s [Ar] 4s00 3d 3d66

To form cations, always remove electrons of highest n value first!

http://mrsec.wisc.edu/Edetc/cineplex/ff/index.html

http://mrsec.wisc.edu/Edetc/cineplex/ff/ff1.html

Dr. S. M. Condren

Quantum Numbers

What is one of the sets of quantum numbers for the 4s electrons in calcium?

n = 4; l = 0; ml = 0; s = +1/2 or

n = 4; l = 0; ml = 0; s = -1/2

Dr. S. M. Condren

Quantum Numbers

What is one of the sets of quantum numbers for the 3p electrons in sulfur?

n = 3; l = 1; ml = +1; s = +1/2 or

n = 3; l = 1; ml = +1; s = -1/2 or

n = 3; l = 1; ml = 0; s = +1/2 or

n = 3; l = 1; ml = 0; s = -1/2 or

n = 3; l = 1; ml = -1; s = +1/2 or

n = 3; l = 1; ml = -1; s = -1/2

Dr. S. M. Condren

Quantum Numbers

What is one of the sets of quantum numbers for the 3d electrons in Fe?

n = 3; l = 2; ml = +2; s = +1/2 or n = 3; l = 2; ml = +2; s = -1/2

or n = 3; l = 2; ml = +1; s = +1/2 or n = 3; l = 2; ml = +1; s = -1/2

or n = 3; l = 2; ml = 0; s = +1/2 or n = 3; l = 2; ml = 0; s = -1/2

or n = 3; l = 2; ml = -1; s = +1/2 or n = 3; l = 2; ml = -1; s = -1/2

or n = 3; l = 2; ml = -2; s = +1/2 or n = 3; l = 2; ml = -2; s = -1/2

Dr. S. M. Condren

Announcements

• You may bring a 4x6 index card with information

• A periodic table and a table of thermodynamic data will be furnished.

• You need to know your TAs name and your section number.

• Photo ID will be required when submitting your exam.

Dr. S. M. Condren

AnnouncementsTeaching Assistant _________________________ Section _____ Name _________________________________ c

General Chemistry 103Hour Exam 2Nov. 6, 2006

ALL WORK MUST APPEAR ON TEST FOR ANY CREDIT.Work includes “stating the question in a mathematical form.”

A box should be drawn around the answer to be graded for a problem.

Dr. S. M. Condren

Announcements

• Last day to drop

• Suzie and Christie have papers to return, please see them after class

Dr. S. M. Condren

Bonus Points

• Exam II – worth 105 points, count as 100

• 5 pts - Available through “Other Lecture Documents” this week, due Friday Nov. 10

• Exam III – worth 105 points, count as 100

• 5 pts - Available through “Other Lecture Documents” later, due Friday Dec. 15

Dr. S. M. Condren

How do we know the configurations of ions? How do we know the configurations of ions?

Determine the Determine the magnetic propertiesmagnetic properties of ions. of ions.

Sample of Fe2O3

Sample of Fe2O3

with strong magnet

Ion ConfigurationsIon Configurations

Dr. S. M. Condren

General Periodic TrendsGeneral Periodic Trends• Atomic and ionic sizeAtomic and ionic size• Ionization energyIonization energy• Electron affinityElectron affinity

Higher effective nuclear chargeElectrons held more tightly

Larger orbitals.Electrons held lesstightly.

Dr. S. M. Condren

Effective Nuclear Charge, Z*Effective Nuclear Charge, Z*

• Atom Z* Experienced by Electrons in Valence Orbitals

• Li +1.28• Be -------• B +2.58• C +3.22• N +3.85• O +4.49• F +5.13

Increase in Increase in Z* across a Z* across a periodperiod

[Values calculated using Slater’s Rules][Values calculated using Slater’s Rules]

Dr. S. M. Condren

Orbital EnergiesOrbital EnergiesOrbital energies “drop” as Z* increasesOrbital energies “drop” as Z* increases

Dr. S. M. Condren

Atomic RadiiAtomic RadiiAtomic RadiiAtomic Radii

Dr. S. M. Condren

Atomic Size

• Size goes UPSize goes UP on going down a group. on going down a group.

• Because electrons are added further from Because electrons are added further from the nucleus, there is less attraction.the nucleus, there is less attraction.

• Size goes DOWNSize goes DOWN on going across a on going across a period.period.

Dr. S. M. Condren

Size Size decreasesdecreases across a period across a period owing to increase in Z*. Each added owing to increase in Z*. Each added electron feels a greater and greater electron feels a greater and greater + charge.+ charge.

LargeLarge SmallSmall

Increase in Z*Increase in Z*

Atomic Radius

Dr. S. M. Condren

Trends in Atomic SizeTrends in Atomic Size

0

50

100

150

200

250

0 5 10 15 20 25 30 35 40

Li

Na

K

Kr

He

NeAr

2nd period

3rd period 1st transitionseries

Radius (pm)

Atomic Number

0

50

100

150

200

250

0 5 10 15 20 25 30 35 40

Li

Na

K

Kr

He

NeAr

2nd period

3rd period 1st transitionseries

Radius (pm)

Atomic Number

Dr. S. M. Condren

Sizes of Transition ElementsSizes of Transition Elements3d subshell is 3d subshell is inside the 4s inside the 4s subshell.subshell.

4s electrons feel a 4s electrons feel a more or less more or less constant Z*.constant Z*.

Sizes stay about the Sizes stay about the same and same and chemistries are chemistries are similar!similar!

Dr. S. M. Condren

Density of Transition MetalsDensity of Transition Metals

0

5

10

15

20

25

3B 4B 5B 6B 7B 8B 1B 2B

Group

Den

sit

y (

g/m

L)

6th period6th period



Dr. S. M. Condren

Li,152 pm3e and 3p

Li+, 60 pm2e and 3 p

+

Ion SizesIon SizesDoes the size goDoes the size goup or down up or down when losing an when losing an electron to form electron to form a cation?a cation?

Dr. S. M. Condren

• CATIONSCATIONS are are SMALLERSMALLER than the than the atoms from which they come.atoms from which they come.

• The electron/proton attraction has The electron/proton attraction has gone UP and so size gone UP and so size DECREASESDECREASES..

Li,152 pm3e and 3p

Li+, 78 pm2e and 3 p

+

Ion SizesIon Sizes

Forming Forming a cation.a cation.

Dr. S. M. Condren

F,64 pm9e and 9p

F- , 136 pm10 e and 9 p

-

Ion Sizes

Does the size go up Does the size go up or down when or down when gaining an electron to gaining an electron to form an anion?form an anion?

Dr. S. M. Condren

• ANIONSANIONS are are LARGERLARGER than the atoms than the atoms from which they come.from which they come.

• The electron/proton attraction has gone The electron/proton attraction has gone DOWN and so size DOWN and so size INCREASESINCREASES..

• Trends in ion sizes are the same as atom Trends in ion sizes are the same as atom sizes. sizes.

F, 71 pm9e and 9p

F-, 133 pm10 e and 9 p

-

Ion SizesForming Forming an anion.an anion.

Dr. S. M. Condren

Trends in Ion SizesTrends in Ion Sizes

Dr. S. M. Condren

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 350

500

1000

1500

2000

2500

1st Ionization energy (kJ/mol)

Atomic NumberH Li Na K

HeNe

ArKr

Trends in Ionization EnergyTrends in Ionization Energy

Dr. S. M. Condren

Electron AffinityElectron AffinityA few elements A few elements GAINGAIN electrons electrons

to form to form anionsanions..

Electron affinity is the energy Electron affinity is the energy involved when an atom gains involved when an atom gains an electron to form an anion.an electron to form an anion.

A(g) + e- ---> AA(g) + e- ---> A--(g) (g)

E.A. = ∆EE.A. = ∆E

Dr. S. M. Condren

Electron Affinity of OxygenElectron Affinity of Oxygen

∆∆E is E is EXOEXOthermic thermic because O has because O has an affinity for an an affinity for an

ee--..

[He] O atom

EA = - 141 kJ

+ electron

O [He] - ion

Dr. S. M. Condren

Electron Affinity of NitrogenElectron Affinity of Nitrogen

∆∆E is E is zero zero for for NN- - due to due to electron-electron-electron electron repulsions.repulsions.EA = 0 kJ

[He] N atom

[He] N- ion

+ electron

Dr. S. M. Condren

Announcements

• You may bring a 4x6 index card with information

• A periodic table and a table of thermodynamic data will be furnished.

• You need to know your TAs name and your section number.

• Photo ID will be required when submitting your exam.

Dr. S. M. Condren

Announcements

• Last day to drop

• Suzie and Christie have papers to return, please see them after class