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Catalyst – February 1s22s1, 2011
1. Define trend.2. Define radius.
Today’s Agenda
Catalyst Review Periodic Table Basics
Worksheet Periodic Trends: Notes and Work
Time Exit Question
HW: ANSWER CHAPTER 6 ASSESSMENT
QUESTIONS 31, 49, 56, 69, 73
Today’s Objectives
SWBAT describe the periodic trends for valence electrons, atomic radius, and electronegativity.
Reward Vote (3rd Period)
Donuts Oreos Chocolate Chip/Sugar Cookies Granola/Fruit Other (tell me what you’d like!)
PERIODIC TRENDS!!!VALENCE ELECTRONS
(CHECK!)ATOMIC RADIUS
ELECTRONEGATIVITY
Valence Electrons
Don’t forget!Valence electrons are the electrons in the outermost energy level.
Let’s look at Bohr Models…
http://www.chemicalelements.com/show/electronconfig.html
Valence Electrons – Right on your PT
Trend for Valence Electrons
Key Point #1: Number of valence electrons increases from 1-8 as you go right across the periodic table.
What is Atomic Radius?
Key Point #2: Atomic radius is how big an atom is and is also known as atomic size.
What is Electronegativity?
Key Point #3: Electronegativity is the ability of an atom to attract electrons to itself in a chemical bond.
How much an atom wants electrons
Graphing Atomic Radius (Size)Draw 2 line graphs
X-axis: Element Y-axis: Atomic Radius (picometers)
Elements and their Atomic Radii (1)
Element Atomic Radius (picometer)
Hydrogen 37
Lithium 152
Sodium 186
Potassium 227
Rubidium 248
Cesium 265
1 picometer = 1 x 10-12 m
Elements and their Atomic Radii (2)
Element Atomic Radius (picometer)
Lithium 152
Beryllium 112
Boron 85
Carbon 77
Nitrogen 75
Oxygen 73
Fluorine 72
Neon 71
1 picometer = 1 x 10-12 m
Atomic Size – Graph 1
0
50
100
150
200
250
300
350
0 1 2 3 4 5 6 7
Element
Ato
mic
Ra
diu
s (
pic
om
ete
r)
H Li
Na K Rb Cs
Atomic Size – Graph 2
0
20
40
60
80
100
120
140
160
0 2 4 6 8 10
Element
Ato
mic
Ra
diu
s (
pic
om
ete
r)
Li Be B C N O FNe
What trend(s) do
you notice?
TRENDS FOR ATOMIC RADIUS Key Point #4: Atomic size INCREASES as you go DOWN the periodic table and DECREASES as you go LEFT TO RIGHT across the periodic table.
Practice Problems
Rank the following elements in order of increasing atomic size based on location on the periodic table (smallest to biggest)
Fr, Sc, P, Pd
F, As, Tl, SP < Sc < Ps < Fr
F < S < As < Tl
Graphing Electronegativity
Draw 2 line graphs X-axis: Element Y-axis: Electronegativity (Paulings)
Elements and their Electronegativity (1)
Element Electronegativity (Paulings)
Hydrogen 2.20
Lithium 0.98
Sodium 0.93
Potassium 0.82
Rubidium 0.82
Cesium 0.79
Francium 0.70
Elements and their Electronegativity (2)
Element Electronegativity (Paulings)
Lithium 0.98
Beryllium 1.57
Boron 2.04
Carbon 2.55
Nitrogen 3.04
Oxygen 3.44
Fluorine 3.98
Electronegativity Graph 1
0
0.5
1
1.5
2
2.5
0 1 2 3 4 5 6 7 8
Element
Ele
ctro
neg
ativ
ity
Electronegativity Graph 2
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 2 4 6 8
Element
Ele
ctro
neg
ativ
ity
What trend(s) do
you notice?
Electronegativity Trends
TRENDS FOR ELECTRONEGATIVITY
Key Point #5: Electronegativity DECREASES as you go DOWN the periodic table and INCREASES as you go LEFT TO RIGHT across the periodic table.
Practice Problems
Rank the following elements in order of increasing electronegativity based on location on the periodic table (smallest to biggest)
Mg, Sr, Be, Ra
Cl, Si, Al, S, P
Ra < Sr < Mg < Be
Al < Si < P < S < Cl
So as you go LEFT to RIGHT… TO SUM IT UP: As you move left to right across the periodic table, positive charge increases so… ELECTRONEGATIVITY INCREASES
Therefore, ATOMIC RADIUS DECREASES
So as you go from TOP to BOTTOM…
TO SUM IT UP: As you go from top to bottom on the periodic table, energy levels (shells) increase so… ATOMIC RADIUS INCREASES Therefore, ELECTRONEGATIVITY DECREASES
How are atomic radius and electronegativity related?
Key Point #5: Atomic radius and electronegativity are indirectly/inversely related.
ELECTRONEGATIVITY
ATOMIC RADIUS
Why is this relationship true? Atoms with HIGH
ELECTRONEGATIVITIES hold their electrons very close!
Sooooo, the atomic radius decreases High or low
electronegativity?
Large or small atomic size?
Why is this relationship true? Atoms with LARGE RADII can’t pull on
their electrons as much Soooo, ELECTRONEGATIVITY decreases!
More Practice!
1. T or F? Atomic size decreases as you move right across the periodic table.
2. T or F? As you move down the Periodic Table, atoms get smaller.
3. Rank the following sets of elements in order of increasing atomic size (small big).
Set A: Bh, Mn, Re, Tc Set B: Sb, I, Ag, Ru Set C: Y, Ti, Sg, Ta
4. Rank the following sets of elements in order of decreasing atomic size (big small).Set A: Cl, At, I, F, Br Set B: Te, Xe, Sn, In
Set C: Rb, K, Sr, Ca
More Practice!
1. T or F? Electronegativity decreases as you move left across the periodic table.
2. T or F? As you move down the Periodic Table, atoms get more electronegative.
3. Rank the following sets of elements in order of increasing electronegativity (small big).
Set A: Bh, Mn, Re, Tc Set B: Sb, I, Ag, Ru Set C: Y, Ti, Sg, Ta
4. Rank the following sets of elements in order of decreasing electronegativity (big small).Set A: Cl, At, I, F, Br Set B: Te, Xe, Sn, In
Set C: Rb, K, Sr, Ca
Exit Question
1. Which element has atoms with the smallest radius: Cl, Se, P, or F?
2. Which element has the largest electronegativity: Ag, Cu, Hg, or Zn?
3. How are atomic radius and electronegativity related?
HW: ANSWER CHAPTER 6 ASSESSMENT
QUESTIONS 31, 49, 56, 69, 73
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