1. Mr. Hollister Holliday Legacy High School Chemistry
The Periodic Table
and Periodic Trends
Mr. Hollister Holliday
Legacy High School
Chemistry

2. Dmitri Mendeleev Ordered elements by atomic mass.
Saw a repeating pattern of properties.
Periodic law —When the elements are arranged in order of increasing relative mass, certain sets of properties recur periodically.
Used pattern to predict properties of undiscovered elements.
Where atomic mass order did not fit other properties, he reordered by other properties.
Te & I

3. Mendeleev’s Periodic Table

4. Mendeleev's Predictions

5. Periodicity Periodic = repeating
When one looks at the properties of elements, one notices a repeating pattern of characteristics & reactivities.
Periodic = repeating

6. Periodicity
= Metal
= Metalloid
= Nonmetal

7. Metals Solids at room temperature, except Hg.
Reflective surface = Luster.
Shiny
Conduct heat.
Conduct electricity.
Malleable.
Can be shaped.
Ductile.
Drawn or pulled into wires.
About 75% of the elements are metals.
Lower left on the table.

8. Nonmetals Found in all 3 states. Poor conductors of heat.
Poor conductors of electricity.
Solids are brittle.
Upper right on the table.
Except H.

9. Properties of Silicon:
Metalloids
Show some properties of metals and some of nonmetals.
Also known as semiconductors.
Properties of Silicon:
Shiny
Conducts electricity
Does not conduct heat well
Brittle

10. The Modern Periodic Table
Determined the atomic numbers of elements from their X-ray spectra (1914)
Arranged elements by increasing atomic number
Killed in WW I at age 28
(Battle of Gallipoli in Turkey)
H.G.J. Moseley ( ) while doing post-doctoral work (with Ernest Rutherford) bombarded X-rays at atoms in increasing number and noted that the nuclear charge increased by 1 for each element. This gave him the idea to organize the elements by increasing atomic number.
Periodic law – elements organized by increasing atomic number on periodic table (1913)
In 1913, Moseley analyzed the frequencies of X -rays emitted by the elements and discovered that the underlying foundation of the order of the elements was atomic number, not atomic mass.
Moseley hypothesized that the placement of each element in his series corresponded to its atomic number Z, which is the number of positive charges (protons) in its nucleus.
Moseley- wavelengths in X-rays determined by the number of protons in the nucleus of the anode atoms
- change anode, change wavelength
Henry Moseley

11. The Modern Periodic Table
Elements are arranged from left to right in order of increasing atomic number
There are 18 vertical columns called Families
There are 7 horizontal rows called Periods.

12. Buy this as a

13. The Modern Periodic Table
Main group = representative elements = “A” groups
Transition elements = “B” groups
all metals
Bottom rows = inner transition elements = rare earth elements
metals
really belong in Period 6 & 7

14. find table that includes rare earth elements

15. Long Form of the Periodic Table

16. = Alkali metals = Alkali earth metals = Noble gases = Halogens
= Lanthanides
= Actinides
= Transition metals
add pictures of elements from text
Tro: Chemistry: A Molecular Approach, 2/e

17. Important Groups - Hydrogen
Nonmetal
Colorless, diatomic gas
very low melting point and density
Excited Hydrogen Gas

18. Important Groups – Alkali Metals
Group IA = Alkali Metals
Hydrogen usually placed here, though it doesn’t really belong
Soft, low melting points, low density
Flame tests ® Li = red, Na = yellow, K = violet
Very reactive, never find uncombined in nature
lithium
sodium
potassium
rubidium
cesium

19. Important Groups - Alkali Earth Metals
magnesium
calcium
beryllium
strontium
barium
Group IIA = Alkali Earth Metals
harder, higher melting, and denser than alkali metals
Mg alloys used as structural materials
flame tests = Ca = red, Sr = red, Ba = yellow-green
reactive, but less than corresponding alkali metal

20. Important Groups – Halogens
Group VIIA = halogens
Nonmetals
Only family with solids, liquids, and gases
All diatomic
Very reactive
fluorine
chlorine
bromine
iodine
astatine

21. Important Groups - Noble Gases
helium
neon
argon
krypton
xenon
Group VIIIA = Noble Gases
all gases at room temperature
very low melting and boiling points
very unreactive, practically inert
very hard to remove electron from or give an electron to

22. States of the Elements (at STP)
Orange = Solid Red = Liquid Purple = Gas

23. Valence Electrons
The electrons in all the sublevels with the highest principal energy levels are called the valence electrons.
Electrons in lower energy levels are called core electrons.
Chemists have observed that one of the most important factors in the way an atom behaves, both chemically and physically, is the number of valence electrons.

24. Valence Electrons, Continued
Rb = 37 electrons = 1s22s22p63s23p64s23d104p65s1
The highest principal energy shell of Rb that contains electrons is the 5th, therefore, Rb has 1 valence electron and 36 core electrons.
Kr = 36 electrons = 1s22s22p63s23p64s23d104p6
The highest principal energy shell of Kr that contains electrons is the 4th, therefore, Kr has 8 valence electrons and 28 core electrons.

25. Practice—Determine the Number of Valence Electrons in an Arsenic, As, Atom (use the Noble Gas shortcut).

26. Practice—Determine the Number of Valence Electrons in an As Atom, Continued.
As Z = 33, therefore 33 e−. 1s
2s 2p
3s 3p 3d
4s 4p 4d 4f 5s
2 e−
+2 = 4e−
+6 +2 = 12e−
= 20e−
= 36e−
The highest occupied principal energy level is the 4th.
The valence electrons are 4s and 4p and there are 5 total.
Therefore, the electron configuration is 1s22s22p63s23p64s23d104p3.

27. Sublevels and the Periodic Table
p1 p2 p3 p4 p5 s2 1 2 3 4 5 6 7 p6
d1 d2 d3 d4 d5 d6 d7 d8 d9 d10
f1 f2 f3 f4 f5 f6 f7 f8 f9 f10 f11 f12 f13 f14

29. Electron Configuration and the Periodic Table
Elements in the same column have similar chemical and physical properties because they have the same number of valence electrons.
The number of valence electrons for the main group elements is the same as the group number.

30. Electron Configuration of The Noble Gases

31. Electron Configuration of The Alkali Metals

32. Electron Configuration of The Halogens32

33. Periodic Trends in the Properties of the Elements

34. Reactivity
For the metals, as you move down a family, reactivity goes up. As you move across a period, reactivity goes down.
Brainiac’s Video
For the nonmetals, as you move down a family, reactivity goes down. As you move across a period, reactivity goes up.
Except for the Noble Gases!!!!

35. Trends in Atomic Size Either volume or radius.
Treat atom as a hard marble.
As you traverse down a column on the periodic table, the size of the atom increases.
Valence shell farther from nucleus.
Effective nuclear charge fairly close.
As you traverse left to right across a period, the size of the atom decreases.
Adding electrons to same valence shell.
Effective nuclear charge increases.
Valence shell held closer.

36. Trends in Atomic Size, Continued

37. Be (4p+ and 4e-) Mg (12p+ and 12e-) Ca (20p+ and 20e-) Group IIA 2e-

38. Li (3p+ and 3e-) Be (4p+ and 4e-) B (5p+ and 5e-) C (6p+ and 6e-)
Period 2
2e-
1e-
3 p+
2e-
4 p+
2e-
3e-
5 p+
Li (3p+ and 3e-)
Be (4p+ and 4e-)
B (5p+ and 5e-)
6 p+
2e-
4e-
8 p+
2e-
6e-
10 p+
2e-
8e-
C (6p+ and 6e-)
O (8p+ and 8e-)
Ne (10p+ and 10e-)

39. Choose the Larger Atom in Each Pair
C or O
Li or K
C or Al
Se or I?

40. Practice—Choose the Larger Atom in Each Pair.
1. N or F
2. C or Ge
3. N or Al
4. Al or Ge

41. Practice—Choose the Larger Atom in Each Pair, Continued.
N or F, N is further left
N or F
C or Ge
N or Al, Al is further down & left
N or F
C or Ge, Ge is further down
N or F
C or Ge
N or Al
Al or Ge? opposing trends

42. Ionization Energy
Minimum energy needed to remove an electron from an atom.
Gas state.
Valence electron easiest to remove.
M(g) + 1st IE  M1+(g) + 1 e-
M+1(g) + 2nd IE  M2+(g) + 1 e-
First ionization energy = energy to remove electron from neutral atom; 2nd IE = energy to remove from +1 ion; etc.

43. Trends in Ionization Energy
As you traverse down a family, the IE gets smaller.
Valence electron farther from nucleus.
As you traverse left to right across a period, the IE gets larger.

44. Trends in Ionization Energy, Continued

45. Example—Choose the Atom in Each Pair with the Higher First Ionization Energy
Al or S, Al is further left
1. Al or S
2. As or Sb
3. N or Si
4. O or Cl, opposing trends
Al or S
As or Sb
N or Si, Si is further down and left
Al or S
As or Sb, Sb is further down

46. Practice—Choose the Atom with the Highest Ionization Energy in Each Pair
1. Mg or P
2. Cl or Br
3. Se or Sb
4. P or Se

47. Practice—Choose the Atom with the Highest Ionization Energy in Each Pair, Continued
1. Mg or P
2. Cl or Br
3. Se or Sb
4. P or Se ?

48. Metallic Character
How well an element’s properties match the general properties of a metal.
In general, metals are found on the left of the periodic table and nonmetals on the right.
As you go left to right across the period, the elements become less metallic.
As you go down a column, the elements become more metallic

49. Metallic Character, Continued
In general, metals are found on the left of the periodic table and nonmetals on the right.
As you traverse left to right across the period, the elements become less metallic.
As you traverse down a column, the elements become more metallic.

50. Trends in Metallic Character

52. Example—Choose the More Metallic Element in Each Pair
Sn or Te, Sn is further left
Sn or Te
P or Sb
Ge or In
S or Br? opposing trends
Sn or Te
P or Sb
Ge or In, In is further down & left
Sn or Te
P or Sb, Sb is further down

53. Practice—Choose the More Metallic Element in Each Pair
Sn or Te
Si or Sn
Br or Te
Se or I

54. Practice—Choose the More Metallic Element in Each Pair, Continued
Sn or Te
Si or Sn
Br or Te
Se or I ?