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04/18/23
One Point Quiz
One quiz per table, list everyone’s name Agree on an answer You have two minutes
04/18/23
Laboratory Reports
Each lab report in Chemistry 115 is due the laboratory after you complete the analysis of your unknown.
Follow the format in the laboratory manual (M5-M6).
The report must be typed or word processed. Deadline for Laboratory Report A
• FRIDAY, January 11 (Week 5)
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Laboratory Reports
Okay to set up your own form following the general format shown in the laboratory manual. There is a template on-line in the class folder.
Only two (2) pages long. Be sure to include your UNKNOWN # and
sign the report.
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Laboratory Reports
Probable other final deadlines• Report B: Monday Week 7• Report C: Monday Week 9• Report D: Monday Week 10
Unknown B: Three possible ions:• Ba2+, Cd2+, Mn2+
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First Ionization Potential (IP)
H
He
Li
BeB
C
NO
F
Ne
Na
Mg
AlSi
PS
Cl
Ar
K
Ca
0
100
200
300
400
500
600
0 5 10 15 20Atomic Number
En
erg
y (k
cal/
mo
l)
Where on the periodic table arethe highest first IP values located?
Where on the periodic table are thelowest first IP values located?
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First Ionization Potential (IP)
lowest
highest
Ionization energy (IE)
The trend isnot perfect
Many inconsistencies can be associatedwith electronic configuration and
changes in orbital spherical symmetry
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kcal/mol
H 313.4
He 567.0
Li 124.4
Be 215.0
B 191.3
C 259.7
N 335.2
O 314.1
F 401.8
Ionization Potential
Identify the trends
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kcal/mol
497.3
118.5
176.3
138.0
188.0
241.8
238.9
299.0
Ne
Na
Mg
Al
Si
P
S
Cl
Ar 363.4
Ionization Potential
Identify the trends
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Size
Atomic Radii (Å)
Na1.90
Mg1.60
Al1.43
Si1.32
P1.28
S1.27
metallic radii
Why does the size decrease,even though the number of electrons are increasing?
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Nucleus-Electron Charge Attraction
e– +++
e– ++++++F =
(e) (Ze)
r2
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Orbital Set Size
xy
z
2px2s
The size of an atom or ion is definedby the radius of the outermost(valence) electrons.
In going across a period,the radial distance of the electrons
in the valence orbitals is about the same.
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The number of protons (nuclear charge)and electrons are both increasing
The orbital set can hold the additional electronswithout having to get larger.
The increase in nuclear charge contracts the orbital setslightly, resulting in a smaller atom.
(going from left to right)
Na11
Mg12
Al13
Si14
P15
S16
Atom Size and Nuclear Charge
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Size
Atomic Radii (Å)
Na1.901.86
Mg1.60
Al1.43
Si1.32
P1.28
S1.27
Cl
1.40
Ar
1.92
What opposing factors cause the size ofphosphorous and sulfur to almost be the same?
metallic radii van der Waals radii
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Electron-Electron Charge Repulsion
e–
e– ++++++
P
S
F =(e) (Ze)
r2
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Nonpolar Covalent Radii (Å)
Na 1.54
Li 1.34
K 1.96
Rb 2.11
Cs 2.25
Orbitals of largerprinciple quantumnumber (n) arelarger and furtherfrom the nucleus.
r =4 2 mZe2
n2 h2
This results in theatom or ion sizeincreasing from
top to bottom.
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Atom and Ion Size
Tends to increase• right to left• top to bottom
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Isoelectronic Species
Isoelectronic atoms and ions have thesame electronic configuration
1s2 2s2 2p6 3s2 3p6
Cl-
181 pm
Ar174 pm
K+
133 pm
ionic and covalent radii
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Isoelectronic Series1s2 2s2 2p6 3s2 3p6
0
0.5
1
1.5
2
2.5
14 16 18 20 22 24
Atomic Number
Rad
ius
(A)
Which atom or ion doeseach point represent?
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Rank the oxygen(II) ion, oxygen atom and oxide ion in terms of size
Nuclearcharge
Number ofelectrons
Ionicradii (Å)
O2+ 8 6
O 8 8
O2– 8 10
0.73
0.44
1.40
Explain the relative sizes.
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Rank the hydride ion, helium atom and lithium ion in terms of size
Nuclearcharge
Number ofelectrons
Ionicradii (Å)
H– 1 2
He 2 2
Li+ 3 2
0.93
0.60
2.08
Explain the relative sizes.
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+2 Ions of the First Transition Series
electrons
NuclearchargeNumber
radii (A)
Ti2+
V2+
Cr2+
Mn2+
Fe2+
Co2+
Ni2+
Cu2+
Zn2+
22 23 24 25 26 27 28 29 30
of 20 21 22 23 24 25 26 27 28
ionic 1.00 0.93 0.94 0.97 0.92 0.89 0.83 0.87 0.88
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+2 Ions of the First Transition Series
0.8
0.9
1
0 2 4 6 8 10d electrons
Rad
ius
(A)
What is the overall trend? Why isn’t the trend perfect?
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Inert Gas ConfigurationsMany atoms gain or lose electrons in attempting
to gain an inert gas configurationHeNeArKrXeRn
Compare the electronic configurations ofO2–, F–, Ne, Na+, Mg2+, Al3+
1s2 2s2 2p6
isoelectronic
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ionoutershell
electrons
outer shellelectronic
configuration
isoelectronicinert gas
S2– 8 3s2 3p
6 argon
Cl– 8 3s2 3p
6 argon
K+ 8 3s2 3p
6 argon
Ca2+ 8 3s2 3p
6 argon
Sc3+ 8 3s2 3p
6 argon
Which of these ions is the smallestand which is the largest?
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Inert Gas Electronic Configuration Rule(ions with the electronic
configuration s2p6)
8
18
octet rule
eighteenelectron rule
(ions with the electron configuration s2d10p6)
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ionoutershell
electrons
outer shellelectronic
configuration
isoelectronicinert gas
Se2– 18 krypton
Br– 18 krypton
Rb+ 18 krypton
Sr2+ 18 krypton
Y3+ 18
4s2 3d
10 4p
6
4s2 3d
10 4p
6
4s2 3d
10 4p
6
4s2 3d
10 4p
6
4s2 3d
10 4p
6 krypton
Eighteen Electron Rule(an extension of the inert gas configuration rule)
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5s2 4d
10 5p
5s2 4d
10 5p
5s2 4d
10 5p
ionoutershell
electrons
outer shellelectronic
configuration
isoelectronicinert gas
I– 18 6 xenon
Cs+ 18 6 xenon
Ba2+ 18 6 xenon
Ions Isoelectronic with Xenon
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Electron Affinity
The tendency of an atom or anion to pick upexcess electron density is a measure of theelectron affinity of that atom.
F(g) + e– F– (g)
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Electron AffinityAtoms which need a few electrons to attainan outer shell inert gas electronic configurationhave high electron affinity.
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Electron AffinityAtoms which tend to lose electrons to attainouter shell inert gas electronic configurationhave low electron affinity.
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Electron Affinity (EA)
O(g) + e– O–(g)
The first electron affinity of an atom usually isexothermic (releases energy).
O–(g) + e– O2– (g)
Why does the second electron affinity alwaysrequire energy?
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Electronegativity (EN)
Relative measure of the tendency of an atom to gain an electron or share an electron with another atom.
Electronegativity is calculated, not measured. One definition is EN = (IP + EA) / 2
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Electron Affinity and Electronegativity
Increases• from the bottom to the top• from the left to the right
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Where would hydrogen belong in the periodic table,if the table was organized by period and electronegativity?Hydrogen Is Electronegative
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