Periodic Table Trends

1
Periodicity

• Periodic Table Trends

2
Remember these groups of the periodic table?
3
Periodic Law

• There are repeating patterns in the chemical and
  physical behavior of elements when organized by
  their atomic number.

4
Classifying Elements by Electron Configuration

• e- play significant role in determining physical
  and chemical properties of elements
• Elements are arranged by their properties
• relationship b/w e- config placement of
  elements in the table

5
How the configurations of the noble gases similar?
He

• 1s2
• 1s22s22p6
• 1s22s22p63s23p6
• 1s22s22p63s23p64s23d104p6
• 1s22s22p63s23p64s23d104p65s24d105p6
• 1s22s22p63s23p64s23d104p65s24d10 5p66s24f145d106p6

2
Ne
10
The outer energy level is completely full!
Ar
18
Kr
36
Xe
54
Rn
86
6
How are the configurations of the alkali metals
similar?

• 1s1
• 1s22s1
• 1s22s22p63s1
• 1s22s22p63s23p64s1
• 1s22s22p63s23p64s23d104p65s1
• 1s22s22p63s23p64s23d104p65s24d10 5p66s1
• 1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67
  s1

They all end in s1
7
Every element in group 15 has what outer electron
configuration?
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Periodic Trends

• These patterns in electron configurations produce
  patterns in properties.
• These patterns are called Periodic Trends.

9

• There are 5 major trends that occur in periodic
  table
• Atomic Mass Atomic Number
• Atomic Size
• Ionic Size
• Ionization Energy
• Electronegativity

10
3 factors that effect Periodic Trends

• 1. Nuclear Charge ( protons)
• More p greater charge which pulls e- closer
  effect s period
• 2. Energy level
• More E levels farther away the valence e-
• effects group
• 3. Shielding effect
• effects group

11
Shielding Effect

• Inner e- blocks the nuclear
• charge from
• reaching
• the
• valence e-
• due ? E Level

12
Atomic Mass Atomic

• Increase from top left to bottom right

13
Atomic Size (radius)
14
Atomic Size
15
Atomic Size - Group trends
H

• Going down a group, atoms add another energy
  level
• ? atoms get bigger.

Li
Na
K
Rb
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Atomic Size - Period Trends

• left to right across a period, the size gets
  smaller.
• e- are in the same energy level but more nuclear
  charge
• ?valence e- are pulled closer by inc in protons.

Na
Mg
Al
Si
P
S
Cl
Ar
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Which atom is bigger Why?

1. Li or Cs
2. Ga or B
3. O or C
4. Be or Ba
5. Si or S

18
What do you think the word Octet means?
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Octet Rule 8

• Gain, lose, or share electrons to
  become STABLE
• like Noble gases s2p6
• Exception energy level 1

20
IONS

• When atoms are trying to obey the octet rule they
  will

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Cation ()

• Atom loses electron cation
• more protons than electrons

Group Obeys Octet Rule How Oxidation Number
Group 1 loses 1 e- 1
Group 2 Loses 2 e- 2
Group 13 Loses 3e- 3
22
Anion (-)

• Atom gained electron anion
• more electrons than protons

Group How atom obey Octet Rule Oxidation Number
Group 15 Add 3 e- 3 -
Group 16 Add 2 e- 2 -
Group 17 Add 1e- 1 -
23
Ionic Size

• Metals
• Determine if their ions are smaller or bigger
  than the neutral atom
• Nonmetals
• Determine if their ions are smaller or bigger
  than the neutral atom

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Metal ION ic Size
1. Smaller 2. Lose valence electrons
25
NonMetal ION ic Size

• Bigger
• Gain valence electrons

26
NonMetal
Metal
27
Which ion in each, is smaller?

• 1. Al3 or P3-
• 2. K or Cs
• 3. O2- or Te2-

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Ionization Energy (1st)

• Energy needed to remove ONE electron from an atom
  .
• i.e. How strongly can atom hold onto its
  valence electrons?

29
Ionization Energy
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Low Ionization Energy

• Easy to steal an electron away
• Analogy Easy to steal a purse away from a
  little old lady.

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High Ionization Energy

• Hard to steal an electron away
• Analogy Hard to steal a purse away from
  someone muscular

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Going Down a Group

• Ionization Energy Decreases.
• Valence e- farther from nucleus not held as
  tight by nucleus
• Bigger atom less E to remove e- lower IE

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Going Across a Period

• Ionization Energy Increases
• 1. atom smaller e- closer to nucleus
• 2. closer to being a noble gas
• ? Smaller atom more E to remove e- higher IE

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Which atom has larger (1st ) Ionization
Energy ?

• 1. Na or S
• 2. Mg or Ba
• 3. Ga or Br
• 4. P or Bi

36
Arrange the following elements in
order of decreasing (1st)
Ionization Energy?

1. Cs, Li, K
2. Cl, Si, P
3. Ca, Ba, Be, Sr

37
Electronegativity bonded elements
likelyhood to WANT to take electron from
another
atom
38
Electronegativity
Like tug of war
39
Going Down a Group

• Electronegativity Decreases
• Distance from nucleus increases
• valence electrons NOT held strongly by
  nucleus

40
Going Across Period

• Electronegativity Increases..
• 1. inc attraction to nucleus
• 2. closer to being a noble gas
• ? it wants an electron

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Which atom has higher Electronegativity?

1. Na or Mg
2. K or Br
3. F or Br
4. Ca or Ga
5. Li or S
6. Br or As

43
Summary
Nuclear charge increases Shielding
increases Atomic radius increases Ionization
energy decreases Electronegativity decreases
Shielding is constant Atomic Radius
decreases Ionization energy increases Electronegat
ivity increases Nuclear charge increases









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SAMPLE PROBLEM
Ranking Elements by Atomic Size
(a) Ca, Mg, Sr
(b) K, Ga, Ca
(c) Br, Rb, Kr
(d) Sr, Ca, Rb
PLAN
Elements in the same group increase in size and
you go down elements decrease in size as you go
across a period.
SOLUTION
These elements are in Group 2A(2).
(a) Sr gt Ca gt Mg
These elements are in Period 4.
(b) K gt Ca gt Ga
Rb has a higher energy level and is far to the
left. Br is to the left of Kr.
(c) Rb gt Br gt Kr
Ca is one energy level smaller than Rb and Sr.
Rb is to the left of Sr.
(d) Rb gt Sr gt Ca
45
SAMPLE PROBLEM
Ranking Elements by First Ionization Energy
(a) Kr, He, Ar
(b) Sb, Te, Sn
(c) K, Ca, Rb
(d) I, Xe, Cs
PLAN
IE decreases as you proceed down in a group IE
increases as you go across a period.
SOLUTION
(a) He gt Ar gt Kr
Group 8A(18) - IE decreases down a group.
(b) Te gt Sb gt Sn
Period 5 elements - IE increases across a period.
(c) Ca gt K gt Rb
Ca is to the right of K Rb is below K.
(d) Xe gt I gt Cs
I is to the left of Xe Cs is further to the
left and down one period.