8.11 electron configurations
TRANSCRIPT
8.11 Electron Configurations8.11 Electron Configurations
Noble Gas Electron Configuration
1s 2s 2p
Ne (Z=10)
Valence electrons (orbitals with highest n)
Innershelle-
Noble gases are unusually stable becausethey have completely filled orbitals
Filled octet: 8e-
They don’t want to gain or lose e-
8.11 Electron Configurations8.11 Electron ConfigurationsNoble Gas Electron Configuration
1s 2s 2p
Ne (Z=10)
To simplify the notation, chemists use thefollowing notation to represent filled innershells:
[Noble Gas Chemical Symbol]
[Ne] stands for 1s22s22p6
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
8.12 e- Configurations & Periodic Table
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Important Point The filling order table
provides a general guide…there are
exceptions…we will discuss them
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Groups run down…Periods run across Table
Group 1
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Groups run down…Periods run across Table
Period 4
Group 1
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Elements in same group have same electron
configurations
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Group 1ns1
Group 17ns2np5
Group 18Noble gases
ns2np6
Excepthelium
1 valence e-
7 valence e-
“Octet”
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Group 1ns1
Group 17ns2np5
Group 18Noble gases
ns2np6
Excepthelium
1 valence e-
7 valence e-
“Octet”
Note: Quantum Number n corresponds to the Period Number
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Group 1ns1
Group 18ns2np6
Group 17ns2np5 *
* Except He
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Refer to “blocks” in the periodic table
according to which orbitals are being filled
s block, p block, d block, f block
s block & p block are Main Group Elements
d block are Transition Metals
f block are Lanthanides & Actinides (Rare- earth elements)
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
s blockMain Group Elements
p block
Filling nsorbitals
Filling nporbitals
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
s block
d blockTransition metals
p block
Filling (n-1)dorbitals
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
s block
d blockTransition metals
f block
p block
Filling (n-2)f orbitals
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
f orbitals start filling after lanthanum (Z=57) &
after actinium (Z=89)
La [Xe]5d16s2
Ac [Rn]6d17s2
Then the f orbitals start filling…# = no. of e-
[Xe]4f#5d16s2
[Rn]5f#6d17s2
Note La & Ac are d block f block
When f orbitals are filled…filling of the d resumes
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Note there are exceptions to the filling table
La [Xe]5d16s2
Ac [Rn]6d17s2
[Xe]4f#5d16s2
[Rn]5f#6d17s2
f block
One electrongoes into the6d orbitalbefore fillingthe 5f
One electrongoes into the5d orbitalbefore fillingthe 4f
You are not responsiblefor knowing this
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
f orbitals start filling after lanthanum (Z=57) &
after actinium (Z=89)
La [Xe]5d16s2
Ac [Rn]6d17s2
Many filling exceptions in the f block…you are not responsible for knowing theexceptions within the f block
Then the f orbitals start filling…# = no. of e-
[Xe]4f#5d16s2
[Rn]5f#6d17s2
f block
When f orbitals are filled…filling of the d resumes
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
s block
d blockTransition metals
f block
p block
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
s block ns#, n comes from period
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
s block ns#, n comes from period1s 1s
2s
4s3s
6s5s
7s
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
p blockp block ns2np# n comes from period
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
p blockp block ns2np#, n comes from period
2p
4p3p
6p5p
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
d blockTransition metals
d block ns2(n-1)d#, n comes from period
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
d blockTransition metals
d block ns2(n-1)d#, n comes from period
4d3d
6d5d
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
d blockTransition metals
d block ns2(n-1)d#, n comes from period
4d3d
6d5d
Note exceptions like Cr & Cu due to half-filled and filled d orbitalsYou are responsible for knowing these
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
f blockf block ns2(n-1)d1(n-2)f#, n comes from period
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
f block4f5f
Many exceptions thoughf block ns2(n-1)d1(n-2)f#, n comes from period
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
f blockf block ns2(n-1)d1(n-2)f# n comes from period
4f5f
Note you are notresponsible for knowing filling exceptions in the f block elements
Many exceptions though
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Write out the electronic configuration for Se?
How many valence electrons does Se have?Se: Z=34 …first we find it on the Table
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Identify the core noble gasconfiguration…[Ar]
Se is in Period 4
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Identify the core noble gasconfiguration…[Ar]
Se is in Period 4
4s2
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Identify the core noble gasconfiguration…[Ar]
Se is in Period 4
4s2 3d10
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Identify the core noble gasconfiguration…[Ar]
Se is in Period 4
4s2 3d10 4p4
1 2 3 4
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Identify the core noble gasconfiguration…[Ar]
Se is in Period 4
4s2 3d10 4p4
1 2 3 4
This totals 34 e- [Ar] gives 18+2+10+4=34
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Write out the electronic configuration for Se?
How many valence electrons does Se have?Se: Z=34
Se: [Ar]3d104s24p4
Se: [Ar]3d 4s 4p
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Write out the electronic configuration for Se?
How many valence electrons does Se have?Se: Z=34
Se: [Ar]3d104s24p4
Se: [Ar]3d 4s 4p
Check: Z=34… 18e-+ 10e-+ 2e-+ 4e- = 34e-
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Write out the electronic configuration for Se?
How many valence electrons does Se have?Se: Z=34
Se: [Ar]3d104s24p4
Se: [Ar]3d 4s 4p
Valence e- are outer shell (highest n) e-
Answer: 6 valence electrons in Se
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
You could determine this directlyfrom the periodic table as well
Group 16ns2np4
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
What element has the electron configuration
[Ar]3d64s2?
Consult the Periodic Table
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
The science behind “The Simpsons”“Homer goes to College”Come on, Mr. Simpson,
you'll never pass this course if you don't know the Periodic Table.
Ehh, I'll write it on my hand.HO! Including all known
Lanthanides and Actinides? HA HA!! Good Luck.
Note: you will be given the Periodic Table on exams and midterms!
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
Do problems on electron configurations
Attend a tutorial this week
Typical questions…how many valence
electrons…how many unpaired
electrons…what is the electron configuration
of “element name”
9.6 Magnetic Properties9.6 Magnetic Properties
9-6 Magnetic Properties
9.6 Magnetic Properties9.6 Magnetic Properties
Electron configurations affect behavior
of an atom in a magnetic field
9.6 Magnetic Properties9.6 Magnetic Properties
Spinning electron generates magnetic field
Spin Up
Spin Down
For “unpaired” single electron In an orbital…net mag. field or
9.6 Magnetic Properties9.6 Magnetic Properties
Spinning electron generates magnetic field
Spin Up
Spin Down
For “paired” electrons in an orbital…mag. fields cancel
9.6 Magnetic Properties9.6 Magnetic Properties
Diamagnetic atom or ion only has
paired electrons
Magnetic fields are cancelled out
Diamagnetic species are weakly
repelled by an external magnetic field
9.6 Magnetic Properties9.6 Magnetic Properties
Paramagnetic atom or ion has unpaired
electrons
Magnetic fields do not cancel out
Paramagnetic species are attracted
into an external magnetic field
9.6 Magnetic Properties9.6 Magnetic Properties
Determine electron configuration to see
if there are unpaired electrons
Mg [Ne] 3s
Paired electrons…diamagnetic
9.6 Magnetic Properties9.6 Magnetic Properties
Determine electron configuration to see
if there are unpaired electrons
Mg [Ne] 3s
Paired electrons…diamagnetic
Al [Ne] 3s 3p
unpaired electron
9.6 Magnetic Properties9.6 Magnetic Properties
Determine electron configuration to see
if there are unpaired electrons
Mg [Ne] 3s
Paired electrons…diamagnetic
Al [Ne] 3s 3p
unpaired electron…paramagnetic
9.6 Magnetic Properties9.6 Magnetic Properties
Would you expect Cl- to be attracted or
repelled by an external magnetic field?
Cl- [Ar] Paired electrons…Diamagnetic
Answer: Weakly repelled by externalmagnetic field
The OThe O++ ion is ____________.ion is ____________.
1. neutral2. diamagnetic3. It doesn’t exist.4. paramagnetic5. doubly charged
The OThe O++ ion is ____________.ion is ____________.
O: [He]2s22p4
O+: [He]2s22p3
Remember Hund’s rule of maximum
multiplicity.Therefore, 3 unpaired electrons
with parallel spins, i.e. O+ is paramagnetic.
What about O- and O2-?
Chapter 9 The Periodic TableChapter 9 The Periodic Table
The Periodic Table & Some Atomic
Properties
Primo Levi1919-1987
9.1 9.1 Classifying the ElementsClassifying the Elements
9-1 Classifying the Elements: The
Periodic Law & The Periodic Table
9.1 9.1 Classifying the ElementsClassifying the ElementsChemistry before the Periodic Table…messy
“…chemistry just now is enough to drive one mad. It gives me an impression of a primeval tropical forest, full of the most remarkable things, a monstrous and boundless thicket, with no way of escape, into which one may well dread to enter.”Friedrich
Wohler1800-1882
9.1 9.1 Classifying the ElementsClassifying the ElementsUntil Periodic Law proposed by Dimitri
Mendeleev & Lothar Meyer:
“Certain sets of properties recur periodicallywhen the elements are arranged in order of increasing atomic mass”
[Note: modern form uses increasing atomic number (Z)]
9.1 9.1 Classifying the ElementsClassifying the ElementsMendeleev and Meyer noticed patterns
Lothar MeyerGerman
Dimitri MendeleevRussian
9.1 9.1 Classifying the ElementsClassifying the Elements
Dimitri Mendeleev1834-1907
9.1 9.1 Classifying the ElementsClassifying the ElementsMendeleev left blanks in his periodic table
for undiscovered elements.
He predicted the properties the unknown
elements should have.
His predictions were confirmed when the
elements were found (e.g., germanium in 1886).
9.1 9.1 Classifying the ElementsClassifying the ElementsMendeleev predicted the properties for Ge
Germanium is in the same family as Si andthey share similar properties
9.1 9.1 Classifying the ElementsClassifying the ElementsMendeleev’s Table used atomic mass values
Blank(Germanium)
Mendeleev predictedproperties like Si
Germanium is in the same family as Si andthey share similar properties…powerful tool
9.1 9.1 Classifying the ElementsClassifying the ElementsModern Periodic Table: arrange according to
atomic number (Z)
9.1 9.1 Classifying the ElementsClassifying the ElementsGroups run down…Periods run across Table
Period 3
Group 14
Mohammed Abubakr, Hyderabad, IndiaMohammed Abubakr, Hyderabad, India
The Biochemical Periodic TableThe Biochemical Periodic Table
Yoshiteru Maeno at Kyoto University
bricks are the number of valence electrons for the neutral form of that element (main group
LEGO
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their Ions
9-2 Metals & Nonmetals & Their Ions
Platinum
Sulfur
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsMake predictions based on e- configurations
Metals Non Metals
Noblegases
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsMetals tend to give up electrons
Metals
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsNonmetals tend to gain electrons
Non Metals
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsNoble gases neither gain nor lose e-
Noblegases
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsRecall noble gas configuration ns2np6
Noblegases
*
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsNoble gases: complete octet ns2np6
Eight valence electrons: complete shell
Noble gas configuration is very stable
4s 4p[Ar]3d104s24p6
Metals lose electrons to achieve ns2np6 stabilityNonmetals gain electrons to achieve ns2np6
stability
Kr (Z=36) [Ar]3d10
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsMetals tend to lose electrons
39.098K19
[Ar]4s1
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsMetals tend to lose electrons
[Ar]4s1
K K+ + 1e-
[Ar]
Noble gasconfigurationfor the cation
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsMetals tend to lose electrons
137.33Ba56
[Xe]6s2
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsMetals tend to lose electrons
[Xe]6s2
Ba Ba2+ + 2e-
[Xe]
Noble gasconfigurationfor the cation
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsNonmetals tend to gain electrons
79.904Br35
[Ar]3d104s24p5
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsNonmetals tend to gain electrons
[Ar]3d104s24p5
Br -Br + 1e-
[Ar]3d104s24p6 = [Kr]
Noble gasconfigurationfor the anion
Kryptonite
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsNonmetals tend to gain electrons
32.06S16
[Ne]3s23p4
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsNonmetals tend to gain electrons
[Ne]3s23p4
S2-S + 2e-
[Ne]3s23p6 = [Ar]
Noble gasconfigurationfor the anion
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsTransition metal ions also lose electrons
47.88Ti22
[Ar]3d24s2
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsTransition metals also tend to lose electrons
Ti Ti2+ + 2e-
[Ar]3d24s2 [Ar]3d2
Note: Electronsare lost fromthe outermost orbital(not the last one filled)
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsTransition metal ions can achieve noble gas
configuration e.g., Ti4+
Ti Ti2+ + 2e-
[Ar]3d24s2 [Ar]3d2
Ti Ti4+ + 4e-
[Ar]3d24s2 [Ar]
Noble gas configuration
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsMost transition metal ions do not achieve
noble gas configuration e.g. Fe2+, Fe3+
Fe Fe2+ + 2e-
[Ar]3d64s2 [Ar]3d6
Fe Fe3+ + 3e-
[Ar]3d64s2 [Ar]3d5
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their Ions
Which would you expect to be more stable
Fe2+ or Fe3+?
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their Ions
Which would you expect to be more stable
Fe2+ or Fe3+?
Answer: Fe3+
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their Ions
Which would you expect to be more stable
Fe2+ or Fe3+?
Answer: Fe3+
Why? Extra stability associated with a
half-filled 3d shell.
Fe2O3
Fe3+
9.2 9.2 Metals Nonmetals & their IonsMetals Nonmetals & their IonsMost transition metal ions do not achieve
noble gas configuration
Cu Cu+ + 1e-
[Ar]3d104s1 [Ar]3d10 = [Ne]3s23p63d10
Pseudo noble gasconfiguration18e- in outer shell
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & Ions
9-3 The Sizes of Atoms & Ions
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsThere are size trends for atoms and ions
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsHow do we define atomic, ionic radius?
Electron probability cloud…border uncertain
We can determine internuclear distances
We define radii based on distance between
two nuclei
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsCovalent Radius (for covalent bonded atoms)
r r
Internuclear distance is2 x atomic radius(same species)
O2 (oxygen molecule)
2r = 143 pm
So r = 71.5 pm
18931893Windsor,Windsor,OntarioOntario
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsIonic Radius (for ionic bonded species)
Internuclear distance issum of the two radii
Na+Cl- (ionic compound)
rNa+ + rCl- = 280 pmInternuclear dist.
rNa+99pm
Na+ Cl-
If you know rNa+…you can calculate rCl-
rCl-181pm
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsMetallic Radius (for metal atoms in crystal)
Crystalline Solid MetalAg Ag
Internuclear distance is2 x metallic radius
(same species)
2r = 288 pmSo r = 144 pm
r r
2r
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsWhat are the radii of Li+ and of I-?
a=600pm
c2 = a2 + a2 = 2a2 = 2(600pm)2 (Pythagorean)c = 849 pm = 4rI-
c
ca
a
r -r -
r -r -
rI- = 212 pm
r -
r -
2r+
a = 2rI- + 2rLi+
600pm=2*212pm+2rLi+
rLi+ = 88 pm
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsThe ions in crystalline LiI are arranged as
shown below. If a = 600pm, what is the
radius of Li+? What is the radius of I-?
a=600pm
I-
Li+
rI- = 212pm
rLi+ = 88pm
8.10 Multielectron Atoms8.10 Multielectron AtomsElectron Screening
Inner shellelectronsscreenouter e-
from fullattraction ofthe nucleus
Outer e-
experiencea lowereffective nuclearcharge
Zeff < ZZeff = Z - S
where S is charge that is screened
8.10 Multielectron Atoms8.10 Multielectron Atomss orbitals are better at screening than p & d
s orbitals > p orbitals > d orbitalss Zeff > p Zeff > d Zeff
Valence electrons will shield each other to aMuch Smaller degree than inner shell electrons
Orbital energy depends on n and Zeff
Screeningstrength(for same n)
2H
2eff
n nhcRZ- E =
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & Ions
Atomic Number
AtomicRadius(pm)
Can we explain the size trends?
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & Ions
Atomic Number
AtomicRadius(pm)
Atomic radius usually decreases fromleft to right across a period in s & p blocks
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
s block
Filling nsorbitals
Filling nporbitals
p block
Putting in valence electronsSo, S ∼ constant while Z increasesZeff increases and radius decreases
rr
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & Ions
Atomic Number
AtomicRadius(pm)
Atomic radius usually increasesfrom top to bottom down a group
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsThere are size trends for atoms and ions
Increasing n down agroup…orbitals get larger
so radius increases
r
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & Ions
Atomic Number
AtomicRadius(pm)
Atomic radius often stays relatively constantacross a period for transition metals
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
d blockTransition metals
Filling (n-1)dorbitals
Putting electrons in an inner shellSo, S increases as Z increasesZeff ∼ constant and radius ∼ constant
r ∼ const.
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsRefer to the periodic table and arrange N, O,
and P in order of increasing atomic radius
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & Ions 9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & Ions
For main group atomsradius decreases across a period
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & Ions
For main group atomsradius decreases across a period
Predict O < N
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & Ions
For main group atomsRadius decreases across a period
Predict O < N
Atomic radius increases down a group
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & Ions
For main group atomsradius decreases across a period
Predict O < N < P
Atomic radius increases down a group
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsRefer to the periodic table and arrange N, O,
and P in order of increasing atomic radius
Predicted: O < N < PActual: 73pm 75pm 110pm
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsCations are smaller than the parent atoms
Cations…lose electron(s)…Z stays constant
Na
r = 186 pm r = 99 pm
+ 1e-Na+
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsAnions are larger than the parent atoms
Anion…gain electron(s)…Z stays constant
Cl-
Cl
r = 99 pm r = 181 pm
+ 1e-
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsFor isoelectronic cations…the more positive
charge…the smaller the ionic radius
Na+ Mg2+
r = 99 pm r = 72 pm
Na+ 1s22s22p6
Z=11Mg2+ 1s22s22p6
Z=12isoelectronic
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsFor isoelectronic anions…the more negative
charge…the larger the ionic radiusCl- [Ne]3s23p6
Z=17P3- [Ne]3s23p6
Z=15isoelectronic
Cl-
r = 181 pm
P3-
r = 212 pm
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsRefer to the periodic table and arrange these
species in order of increasing size: Na+,
Mg2+, O2-, F-, Ne
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsDetermine e- configurations from table
All species have [Ne] configuration
Na+Mg2+O2-F-Ne
For isoelectric configurations radius will increasewith decreasing Z
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsRefer to the periodic table and arrange these
species in order of increasing size: Na+,
Mg2+, O2-, F-, Ne
Mg2+ < Na+ < Ne < F- < O2-
Z=12 11 10 9 8
Answer:
Increasing radiusActual: 72pm 99pm 71pm 133pm 140pm
?
9.4 Ionization Energy9.4 Ionization Energy
9-4 Ionization Energy
e-
Energy required to strip an electronfrom a gaseous state atom (or ion)
ΔEIE = ?
9.4 Ionization Energy9.4 Ionization Energy
Ionization energy for H-like species
n=1
n=2
n=3n=4n=5n=∞
hνAtom absorbsphotonΔEIE=hν
E
2H
2
IE 1hcRZ E =Δ
H-like speciesOnly one electron
From ground state
9.4 Ionization Energy9.4 Ionization Energy
Definition
e-
Energy required to strip an electronfrom a gaseous state atom (or ion)
Not spontaneous…requires energy input
Ionization Energy = I
9.4 Ionization Energy9.4 Ionization Energy
In = nth Ionization energy...remove nth e-
Al(g) Al+(g) + 1e-
Al+(g) Al2+(g) + 1e-
I1=577.6 kJ/mol
I2=1,817 kJ/mol
Al2+(g) Al3+
(g) + 1e- I3=2,745 kJ/mol
Al3+(g) Al4+
(g) + 1e- I4=11,580 kJ/mol
[Ne] noble gas configuration…extra stable
9.4 Ionization Energy9.4 Ionization Energy
I depends on Zeff and n
2H
2eff
nhcRZ I =
Larger Zeff…higher I…e- held more tightly
Higher n…lower I…outer e- held less tightly
22eff n
1 I and Z I ∝∝
9.4 Ionization Energy9.4 Ionization Energy
I 1kJ
/mol
Atomic No. (Z)
Periodic Trends for II generally increases across a period
I increases as Zeff increases across a period
8.12 e8.12 e-- Configurations & The Periodic TableConfigurations & The Periodic Table
s block
Filling nsorbitals
Filling nporbitals
p block
Putting in valence electronsSo, S ∼ constant while Z increasesZeff increases
II
9.4 Ionization Energy9.4 Ionization Energy
I 1kJ
/mol
Atomic No. (Z)
Periodic Trends for II generally decreases down a group
I decreases as n increases down a group
9.4 Ionization Energy9.4 Ionization Energy
There are IE trends
I
9.4 Ionization Energy9.4 Ionization Energy
There are IE trends
n
Zeff increasesonly slightlydown a group
I
9.4 Ionization Energy9.4 Ionization Energy
There are some exceptions
9.3 9.3 The Sizes of Atoms & IonsThe Sizes of Atoms & IonsWe would predict I1 Mg < I1 Al
9.4 Ionization Energy9.4 Ionization Energy
There are some exceptions
I1 = 737.7 kJ/mol Mg
I1 = 577.6 kJ/mol Al
Why lower?
Mg [Ne]3s2
Al [Ne]3s23p1
Easier to pull the electron from a higherenergy p orbital thana lower energy s orbital
Al is lower???
9.4 Ionization Energy9.4 Ionization Energy
Remember that electrons are ionized from
the orbital with the highest n
This is not necessarily the last orbital to be
filled
If there are different types of orbitals with the
same n, the e- is ionized from the highest
energy orbital
9.4 Ionization Energy9.4 Ionization Energy
Remember that electrons are ionized from
the orbital with the highest n
This is not necessarily the last orbital to be
filled
If there are different types of orbitals with the
same n, the e- is ionized from the highest
energy orbital
Lower energy s < p < d Higher energy
9.4 Ionization Energy9.4 Ionization Energy
Example
Sc [Ar]3d14s2
Last e- added
First e- removed
Sc [Ar]3d14s2 Sc+ [Ar]3d14s1 + 1e-
Sc+ [Ar]3d14s1 Sc2+ [Ar]3d1 + 1e-
Sc2+ [Ar]3d1 Sc3+ [Ar] + 1e-
9.4 Ionization Energy9.4 Ionization Energy
Typical problems…refer to the periodic table
and arrange elements in expected order of
increasing first ionization energy I1
Attend tutorials for examples
9.5 Electron Affinity9.5 Electron Affinity
9-5 Electron Affinity
e-
Energy change when an electron is addedto a gaseous state atom (or ion)
ΔEEA = ?
9.5 Electron Affinity9.5 Electron Affinity
Definition
e-
Energy change when an electron is addedto a gaseous state atom (or ion)
Electron Affinity = EA
9.5 Electron Affinity9.5 Electron Affinity
EA is often negative
This means energy is given off
(exothermic)
Note that ionization energy was always
positive…it required input of energy
9.5 Electron Affinity9.5 Electron Affinity
F(g) + 1e- F-(g) EA=-328 kJ/mol
1s22s22p5 1s22s22p6
9.5 Electron Affinity9.5 Electron Affinity
EAn = nth Electron Affinity...add nth e-
O(g) + 1e- O-(g) EA1=-141.0 kJ/mol
O-(g) + 1e- O2-
(g) EA2=+744 kJ/mol
Positive because it ishard to add a second electron due to repulsion
9.5 Electron Affinity9.5 Electron Affinity
Electron affinity trends are harder to
discern
It is easy to get confused!
A high affinity for electrons means a
large negative electron affinity
9.5 Electron Affinity9.5 Electron AffinityEA tends to become less negative (lower affinity)down a Group
9.5 Electron Affinity9.5 Electron Affinity
Highest affinities (most negative EA)are found in Group 17
9.5 Electron Affinity9.5 Electron Affinity
Highest EA values are found ingroup 17…ns2np5…readily gain one e-
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
9-7 Periodic Properties of the Elements
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
Summary of Atomic Properties Fig.9.11
Arrowsindicateincreasing
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
Summary of Atomic Properties Fig.9.11EA becomes more negative
Arrowsindicateincreasing
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
Summary of Atomic Properties Fig.9.11EA becomes more negative
We can understand the trends in terms ofZeff (screening); n (orbital size); e- repulsion
Arrowsindicateincreasing
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
Periodicity…Predict Properties Physicalpropertiesoftenchangeuniformlydown agroup
e.g., melting &boilingpoints
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
Periodicity…Predict Properties
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
Periodicity…Predict Properties Halogensdiatomice.g.,Cl2Br2I2
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
Periodicity…Predict Properties
Can we predict the melting point of Br2?Estimated mp = (172K+387K)/2 = 280K
Actual mp for Br2 = 266KNot
Too bad!
Table 9.5
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
Periodicity…Predict Properties
Try predicting the boiling point of Br2 by averaging
Example 9-5 pg. 360
Table 9.5
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
As you learn reactions you will see trendsLEO the lion says GER
LEO = loss of electrons Oxidation GER = gain of electrons Reduction
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
As you learn reactions you will see trendsGroups 1 & 2Metals…lose e-
e- loss is OxidationGroup 1 & 2 Metalsare generallygood “reducing agents”A reducing agent undergoesoxidation…but drives reduction (gainof e- by another species)
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
As you learn reactions you will see trends
Group 17Nonmetals…gain e-
They undergo reduction(gain of electrons)
They act as oxidizing agents
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
As you learn reactions you will see trends
Group 17Nonmetals…gain e-
They undergo reduction(gain of electrons)
They act as oxidizing agents(they are reduced but driveoxidation in another species)
9.7 Periodic Properties of the Elements9.7 Periodic Properties of the Elements
In Science, we use models to predict & we
test the predictions
Periodic Tableis central forunderstanding Chemistry