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One Point Quiz

One quiz per table, list everyone’s name Agree on an answer You have two minutes

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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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