Transcript Catalyst – September, 7(1+1) 2009 - stroh

Catalyst – February 1s22s1, 2011
1.
2.
Define trend.
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





rd
(3
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)
1 picometer = 1 x 10-12 m
Element
Atomic Radius (picometer)
Hydrogen
37
Lithium
152
Sodium
186
Potassium
227
Rubidium
248
Cesium
265
Elements and their Atomic Radii (2)
1 picometer = 1 x 10-12 m
Element
Atomic Radius (picometer)
Lithium
152
Beryllium
112
Boron
85
Carbon
77
Nitrogen
75
Oxygen
73
Fluorine
72
Neon
71
Atomic Size – Graph 1
Atomic Radius (picometer)
350
300
250
200
150
100
50
0
0
1
H
2
Li
3
Na
4
K
Element
5
Rb
6
Cs
7
Atomic Size – Graph 2
Atomic Radius (picometer)
160
140
120
100
80
60
40
20
0
0
Li
2
Be
B
C4
6
N
O
Element
F
8
Ne
10
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 P < Sc < Ps < Fr
F, As, Tl, S
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
2.5
Electronegativity
2
1.5
1
0.5
0
0
1
2
3
4
Element
5
6
7
8
Electronegativity Graph 2
Electronegativity
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0
2
4
Element
6
8
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 Ra < Sr < Mg < Be
Cl, Si, Al, S, P 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.
ATOMIC RADIUS
ELECTRONEGATIVITY
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.
2.
3.
T or F? Atomic size decreases as you move right across
the periodic table.
T or F? As you move down the Periodic Table, atoms get
smaller.
Rank the following sets of elements in order of increasing
atomic size (small  big).
Set A: Bh, Mn, Re, Tc
Set C: Y, Ti, Sg, Ta
4.
Set B: Sb, I, Ag, Ru
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.
2.
3.
T or F? Electronegativity decreases as you move left
across the periodic table.
T or F? As you move down the Periodic Table, atoms get
more electronegative.
Rank the following sets of elements in order of increasing
electronegativity (small  big).
Set A: Bh, Mn, Re, Tc
Set C: Y, Ti, Sg, Ta
4.
Set B: Sb, I, Ag, Ru
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.
2.
3.
Which element has atoms with the smallest
radius: Cl, Se, P, or F?
Which element has the largest
electronegativity: Ag, Cu, Hg, or Zn?
How are atomic radius and
electronegativity related?
HW: ANSWER CHAPTER 6 ASSESSMENT
QUESTIONS 31, 49, 56, 69, 73