1. Review Unit 1 (Chp 6,7): Atoms, Electrons, & Periodicity
Chemistry, The Central Science, 10th edition
Theodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten
Review Unit 1 (Chp 6,7): Atoms, Electrons, & Periodicity
John D. Bookstaver
St. Charles Community College
St. Peters, MO
 2006, Prentice Hall, Inc.

2. Development of Atomic Models
1803 Dalton
Atomic Theory
1904 Thomson
Plum Pudding +
1911 Rutherford
Nuclear Model
These illustrations show how the atomic model has changed as scientists learned more about the atom’s structure.

3. same # of protons (& electrons), but different # of neutrons
Isotopes
element:
same or different
mass:
same or different
why?
same # of protons (& electrons), but different # of neutrons 1 H 2 1 H 3 1 H
protium
deuterium
tritium

4. Average Atomic Mass Avg. Mass = (Mass1)(%) + (Mass2)(%) …
average atomic mass: calculated as a weighted average of isotopes by their relative abundances.
lithium-6 (6.015 amu), which has a relative abundance of 7.50%, and
lithium-7 (7.016 amu), which has a relative abundance of 92.5%.
amu = 1/12 mass of C amu = X10^-24 grams
(6.015)(0.0750) + (7.016)(0.925) = 6.94 amu
Avg. Mass = (Mass1)(%) + (Mass2)(%) …

5. isotopes separated by difference in mass
Mass Spectrometry
isotopes separated by difference in mass

6. Development of Atomic Models
1803 Dalton
Atomic Theory
1904 Thomson
Plum Pudding +
What evidence?
1911 Rutherford
Nuclear Model
These illustrations show how the atomic model has changed as scientists learned more about the atom’s structure.
1913 Bohr
Shell Model
1926 Quantum Mechanical Model

7. Atomic Emission Spectra
5.3
Atomic Emission Spectra
elements give discrete lines of E & f.
(only specific colors of energy & frequency)

8. Bohr’s Shell Model (1913–Niels Bohr)
electrons occupy only specific levels (or shells)
of “quantized” energy
(& wavelength & frequency)
Electrons as Waves
quantized into specific multiples of
wavelengths,
but none in between.

9. Bohr’s Shell Model ∆E EXCITED state
e–’s emit (–) energy, move back to inner levels
(n=5 to n=2)
e–’s absorb (+) energy, move to outer levels
(n=2 to n=5)
GROUNDstate 5 4 3 2 ∆E 2 2
Which transition shows a light wave of the greatest energy?
n=5 to n=2

10. Electromagnetic SpectrumY G B I V
Electromagnetic Spectrum
Lowest Energy
Highest Energy
(higher ) (shorter )
All EM radiation travels at the speed of light (c),  108 m/s.
c = 
E = h
(of 1 photon)

11. + 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2 nucleus Aufbau: Fill lowest energy
orbitals first.
1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p2
Hund:
1 e– in equal orbitals before pairing
()
(3d fills after 4s) ?
Pauli Exclusion:
-Where should we start placing electrons first? -Opposite spin alleviates repulsion. -All single before double.
no e–’s same props
(opp. spin) (↑↓)
nucleus +

12. species are attracted by a magnet (caused by unpaired electrons).
Paramagnetic:
species are attracted by a magnet (caused by unpaired electrons).
Fe: [Ar] ↑↓ ↑↓ ↑ ↑ ↑ ↑
4s d
Diamagnetic:
species are slightly repelled by magnets
(caused by all paired electrons)
Zn: [Ar] ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓

13. d block metals lose their outer s electrons before any core d electrons to form ions.
Fe 1s2 2s2 2p6 3s2 3p6 4s2 3d6
Fe2+ 1s2 2s2 2p6 3s2 3p6 3d6
Fe3+ 1s2 2s2 2p6 3s2 3p6 3d5
d block (trans. metals) have colored ions due to light excited e– movement in d orbitals

14. Other Aspects Ar, K+, Ca2+, S2–, Cl–
List 3 species isoelectronic with Ca2+ & S2–.
P3– , Cl– , Ar, K+ , Sc3+ , Ti4+, V5+, Cr6+, Mn7+
Arrange the following species by increasing size:
Ar, K+, Ca2+, S2–, Cl–
Ca2+ < K+ < Ar < Cl– < S2–

15. SPECTROSCOPIC TECHNIQUE
Spectroscopy
SPECTROSCOPIC TECHNIQUE
EM REGION
APPLICATION
Molecular Structure by molecular Rotation
Microwave
Microwave
Types of bonds by bond Vibration IR
Infrared
Vis/UV Atomic Emission Spectra (lines of frequencies/colors)
Visible & Ultraviolet
Transition of e–’s between energy levels
Ionization of e–’s shows e– configuration
PES (Photoelectron Spectroscopy)
X-ray
WATCH this 6 min Video Explanation of PES at HOME.

16. Photoelectron Spectroscopy (PES)
Which peak is H and which is He?
higher peak = more e–’s
1s2
Relative # of e–’s He
1s1 H
Binding Energy
...or Ionization Energy
(required to remove e–’s)
(MJ/mol)
 further left = more energy required
(stronger attraction
due to more protons)

17. Photoelectron Spectroscopy (PES)
Which peak is H and which is He?
2p6
higher peak = more e–’s ? Ne
1s2
Identify the element
& e-config
Relative # of e–’s He
1s1
1s2
2s2 H
Binding Energy
...or Ionization Energy
(required to remove e–’s)
(MJ/mol)
 further left = more energy required
(stronger attraction
due to more protons)

18. PES (A) PES (B) 3d10 2p6 3p6 1s2 2s2 3s2 4s2 4p2 Ge n = 1 n = 2 n = 3
Identify element (A)
3d10
2p6
3p6
1s2
2s2
3s2
4s2
4p2 Ge
n = 1
n = 2
n = 3
n = 4
WS #1,5
PES (B)
Identify element (B)
4s1 ? K

19. Chemistry, The Central Science, 10th edition
Theodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten
Review Unit 1 (Chp 7): Periodicity …or… Periodic Trends in Atomic Properties
John D. Bookstaver
St. Charles Community College
St. Peters, MO
 2006, Prentice Hall, Inc.

20. (explains all periodic trends and properties)
We will explain observed trends in
Atomic (and Ionic) Radius
Ionization energy
Electronegativity
size
lose e–
attract e–
Zeff & shielding
(explains all periodic trends and properties)

21. Zeff & Shielding attraction shielding Zeff Na atom
effective nuclear charge, (Zeff):
Zeff = Z − S
Z = nuclear charge (+proton’s)
S = shielding
(core e–’s)
attraction
shielding
Zeff
shielding, (S):
inner core e–’s shield valence e–’s from nuclear attraction.
Z = +11
+11
Zeff = +1
Na atom

22. decreases across a period
Atomic Radius
att.
=shield
Zeff
decreases across a period
-due to increasing Zeff
(more protons)
-due to
increasing shielding
(more energy levels)
increases down a group
att.
shield
=Zeff

23. Ionic Radius Why? Cations are smaller than atoms.
loses a shell
core shell closer to nucleus
new valence e– ‘s less shielded
(greater Zeff)
Anions are larger than atoms.
electrons are added and repulsions are increased
(same Zeff & same shielding)

24. Ionization Energy (IE)
energy required to remove an electron
more energy to remove each electron
IE1 < IE2 < IE3, …
look for a huge jump in IE
once all valence e–’s are removed, the next e– is on an inner level with attraction (shielding & Zeff).
huge jump in IE4 b/c 4th e– on inner level
(must have 3 valence e–’s)

25. increases across a period
Trends in First IE
IE tends to…
-due to increasing Zeff
(more protons)
increases across a period
att.
=shield
Zeff
-due to
increasing shielding
(more energy levels)
decreases down a group
att.
shield
=Zeff

26. Trends in Electronegativity (EN)
-ability of an atom to attract electrons when bonded with another atom.
increases across a period
-greater Zeff
-more shielding
(more energy levels)
decreases down a group

27. Periodic Trends (Summary)
Electronegativity
Can you explain all of this in terms of p’s and e’s?
Zeff & shielding
Electronegativity
WS #2,3
Atomic radius