1. Chapter 7 Periodicity Chemistry, The Central Science, 10th edition
Theodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten
Chapter 7 Periodicity
John D. Bookstaver
St. Charles Community College
St. Peters, MO
 2006, Prentice Hall, Inc.
“Tweaked”
by Robert Hernandez
Seabreeze Highschool
2015

2. Match the constants with their value. Which does NOT have units?
Avagadro’s #
Planck’s Constant
Speed of Light
Faraday’s Constant
___ x 10-34
___ 3.00 x 108
___ 96,500
___ x 1023 ?
B m2 kg / s
C m/s
D C/mol A

3. Development of Periodic Table
Elements in the same group generally have similar chemical properties.
(though not identical)

4. “Father” of the Periodic Table
“The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.”
Dimitri
Mendeleev
Arranged elements by atomic weight.
The FIRST periodic table 

5. Development of Periodic Table
Mendeleev predicted the discovery of germanium (which he called eka-silicon) as an element with an atomic weight between that of zinc and arsenic, but with chemical properties similar to those of silicon.

6. Smart uncle who fixed the mistakes of the “Father” of the Periodic Table
..The insides of all the atoms are very much alike, and from these results it will be possible to find out something of what the insides are made up of. 
Henry Moseley
Rearranged Mendeleev’s table by atomic number.
Moseley’s spectrum research 

7. Periodic Trends
Recognize the underlying reasons explaining observed trends in…
Effective Nuclear Charge (shielding)
2. Atomic and Ionic Size.
3. Ionization energy
4. Electron affinity (& Electronegativity)

8. Periodic Trends Driving Forces
Attract
Repel + - - -

9. Periodic Trends Driving Forces
DISTANCE
CHARGE
Strength - -
Strength + + - + +

10. 1. Shielding (Effective Nuclear Charge)
shielding effect: inner electrons protect the outer electrons from the nuclear charge.
effective nuclear charge, (Zeff):
Z is atomic number S is a shielding constant
across a period
Zeff = Z − S
Na atom -
Valence electron (-1)
Outer electron
10-
[Ne] core (10-)
Inner electrons
11+
Nucleus (11+)
Zeff = Z − S 1 11 10

11. 1. Shielding (Effective Nuclear Charge)
Least
Most

12. decreases across a period
2. Sizes of Atoms
decreases across a period
Because Zeff increases (more protons)
Because energy levels (n) increase
increases down a group

13. 2. Sizes of Atoms Smallest Largest
The DOWNWARD increase is much more dramatic than ACROSS.

14. Rank these atoms from SMALLEST to LARGEST
___
___  LARGEST ? F O Cl S

15. 2a. Sizes of Ions
(in pm) -
Cations are smaller than their neutral atoms, because…
outermost electron(s) are removed and the atom loses a shell
excess protons
(greater Zeff)
156 60 Li
Li+ -
191 95 Na
Na+
238
133 - K K+

16. 2a. Sizes of Ions Anions are larger than their neutral atoms, because…
(in pm)
Anions are larger than their neutral atoms, because…
electrons are added and repulsions are increased.
excess electrons
(less Zeff) F- - F 62
133
Cl- - Cl
102
181
Br - - Br
120
196

17. decreases across a period
2a. Sizes of Ions
decreases across a period
increases down a group

18. 2a. Sizes of Ions
Smallest
Largest

19. K, K+, Na, Na+ Rank these Atoms and ions from SMALLEST to LARGEST ?
___
___  LARGEST ?
Na+ Na K+ K

20. F, F-, Cl, Cl- Rank these ATOMS and IONS from SMALLEST to LARGEST ?
___
___  LARGEST ? F F- Cl
Cl-

21. 3. Ionization Energy (IE)
Amount of energy required to remove an electron from the ground state of a gaseous atom or ion.
First ionization energy is that energy required to remove first electron.
Second ionization energy is that energy required to remove second electron, etc.

22. 3. Ionization Energy (IE)
It requires more energy to remove each successive electron.
When all valence electrons have been removed, the IE takes a huge jump.
WHY?

23. Trends in FIRST Ionization Energy (IE) increases across a period
WHY?
decreases down a group

24. Trends in First IE IE tends to… .. increase across a period
More Zeff, no extra shielding
.. decrease down a group
more energy levels cause more shielding from inner electrons as valence electrons are farther from the nucleus.

25. notice Boron (5) and Oxygen (8)

26. IE and Boron’s “dip” Be B 1s 2s 2p 1s 2s 2p4 Be
9.0 1s 2s 2p 5 B
10.8 1s 2s 2p
Removing an electron from a “p” orbital is easier than from the tighter “s” orbital. 26

27. IE and Oxygen’s “dip” N O 1s 2s 2p 1s 2s 2p7 N
14.0 1s 2s 2p 8 O
16.0 1s 2s 2p
Removing an electron from a filled “p” orbital is easier because of the other electron’s repulsion. 27

28. 3. Ionization Energy (IE)
Fluorine has the HIGHEST IE
Largest F
Smallest

29. 4. Electron Affinity Energy change when; 1 mol of gaseous atoms…- -
Energy change when;
1 mol of gaseous atoms…
gains 1 mol of electrons…
to form 1 mol of gaseous ions.
Cl(g) + e−  Cl−(g) ∆E = -349 kJ/mol - - - - -

30. 4. Electron Affinity Cl(g) + e−  Cl−(g) ∆E = -349 kJ/mol
∆E > 0 (+) endothermic (unstable, doesn’t form)
∆E < 0 (–) exothermic (more –, more stable)
DE = Ef − Ei 30

31. Trends in Electron Affinity (EA)
Generally, electron affinity becomes more exothermic across a period.
(many exceptions caused by orbital issues)
more neg. across a period
less neg. down a group

32. Fluorine has the HIGHEST EA too.
4. Electron Affinity
.. MOST NEGATIVE
Fluorine has the HIGHEST EA too. F
LEAST
Negative…

33. Electron Affinity Ionization Energy
IE measures the ease with which an atom loses an electron.
E always +,
lower is easier.
EA measures the ease with which an atom gains an electron.
E > 0 or E < 0 (–),
more – is easier.
(more exothermic)

34. Trends in Electronegativity (EN)
ability of an atom to attract electrons when bonded with another atom.
increases across a period
decreases down a group

35. Fluorine has the HIGHEST EN .
Electronegativity
MOST
Fluorine has the HIGHEST EN . F
LEAST

36. Group Trends

37. Group 1: Alkali Metals Soft, metallic solids. Found only as compounds.
Low densities and melting points.
Lowest ionization energies.
Reactivity tends to increase as go down a group.
Why low IE’s?

38. Group 1: Alkali Metals
Their reactions with water are famously exothermic.
Produce bright colors when placed in flame.

39. Group 2: Alkaline Earth Metals
Higher densities and melting points than alkali metals.
Low ionization energies, but not as low as alkali metals.

40. Group 2: Alkaline Earth Metals
Be does not react with water, Mg reacts only with steam, but others react readily with water.
Reactivity tends to increase as go down a group.

41. Group 17 (VIIA): Halogens
Large, negative EA
Large EN
Therefore, tend to oxidize (take e-) other elements easily

42. Group 18 (VIIIA): Noble Gases
Huge ionization energies
Positive EA (zero EN)
Therefore, relatively unreactive
Monatomic gases

43. Group 18 (VIIIA): Noble Gases
Xe forms three compounds:
XeF2
XeF4 (at right)
XeF6
Kr forms only one stable compound:
KrF2
The unstable HArF was synthesized in 2000.

44. Properties of Metal, Nonmetals, and Metalloids

45. Metals vs. Nonmetals
Differences between metals and nonmetals tend to revolve around these properties.

46. Metals Compounds formed between metals and nonmetals tend to be ionic.
Metal oxides tend to be basic in water.

47. Nonmetals
Compounds formed between nonmetals only are molecular (covalent) compounds.
Most nonmetal oxides are acidic in water.

48. Metalloids Have some characteristics of metals, some of nonmetals.
For instance, silicon looks shiny, but is brittle and is a semi-conductor.

49. And, Finally… PES Z
Dispense, I do.

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

51. Photoelectron Spectroscopy (PES)
2. What element is this?
2p6 Ne
1s2
Relative # of e–’s He
1s1
1s2
2s2 H
Binding Energy
Draw this spike line on Graph .
Watch the proportions.
(eV or MJ)

52. 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
PES (B)
Identify element (B)
4s1 ? K

53. 4. Write the complete electron configuration of element (X), and identify the element.
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1 Ga
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1
PES worksheet
PES (X)
3d10
2p6
3p6
4s2
1s2
2s2
4p1
3s2