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Catalyst – February 13, 2012
Monday Mystery Element!
1. Easily magnetized2. Important for human
nutrition by preventing anemia
3. Can become radioactive and emit gamma rays (can treat cancer)
Catalyst – February 13, 2012
Monday Mystery Element!
1. Easily magnetized (like your heart is for Chemistry)
2. Important for human nutrition by preventing anemia
3. Can become radioactive and emit gamma rays (can treat cancer)
COBALT!
Today’s Agenda
Catalyst Review Quiz 2.1 Notes: Bohr Models and Periodic
Trends Work Time Exit Question
HOMEWORK:ATOMIC TRENDS WORKSHEET
Today’s Objectives
SWBAT draw Bohr Models for the first 20 elements like pros!
SWBAT describe the periodic trends for valence electrons, atomic radius, and electronegativity.
Quiz 2.1 Grade Averages
2nd Period: 72.5% (D) 3rd Period: 71.6% (D) 5th Period: 64.9% (F)
FYI: Ms. Stroh added 5 points to the grade you see
on your paper.
Quiz 2.1 Champs
1st Place (102!): Ryan Craigie (3rd)
2nd Place (97): Josh Hayes (3rd), Destiny Rhea (3rd)
3rd Place: Jaymie Mayberry (3rd)
NOTES:BOHR MODELS
Bohr Models of Atoms
Key Point #1: A Bohr model depicts an atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus
16 p+
16 no
Sulfur: 16 protons
16 neutrons
16 electrons
Energy Levels
Key Point #2: Energy levels (or shells) are paths around the nucleus where electrons travel Energy levels are also known as orbits
Energy increases as you move further from the nucleus
Valence Electrons
Key Point #3: Valence electrons (ve-) are electrons in the outermost energy level They are the furthest from the nucleus
An atom could have 1 ve-, 2 ve-, 3 ve-, etc.
Steps to Making a Bohr Model
1. Determine the number protons, neutrons, and electrons in the atom
2. Draw the nucleus (circle) with # p+ and # no
inside3. Draw the first energy level (circle around
nucleus) and draw up to 2 dots (electrons)4. If needed, draw second energy level (second
circle) and draw up to 8 dots (electrons)5. If needed, draw third energy level (third
circle) and draw up to 8 dots (electrons)6. If needed, draw fourth energy level (fourth
circle) and draw up to 18 dots (electrons)
CHECK OVER YOUR BOHR MODELS
DO YOU HAVE ANYQUESTIONS???
NOTES SECTION:PERIODIC TRENDS!!!VALENCE ELECTRONS
ATOMIC RADIUSELECTRONEGATIVITY
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved..
Although the weather changes from day to day, the weather you experience is related to your location on the globe.
CHEMISTRY & YOUCHEMISTRY & YOU
How are trends in the weather similar to trends in the properties of elements?
Periodic Trends
Key Point #4: There are trends/patterns on the periodic table that help us both compare and contrast elements.
Note-Taking Strategy
Make a T-chart in your notes – like this…. Vocab Word Periodic Trend
Vocab Words (Left)
1. Valence electrons: electrons in the outermost (or outside/biggest) energy level
2. Atomic radius: how big an atom is, also known as atomic size
3. Electronegativity: the ability of an atom to attract electrons to itself in a chemical bond; how much an atom wants electrons
Electronegativity Values for Selected Elements in Paulings
H 2.1
Li 1.0
Be1.5
B2.0
C2.5
N3.0
O3.5
F4.0
Na 0.9
Mg1.2
Al1.5
Si1.8
P2.1
S2.5
Cl3.0
K 0.8
Ca1.0
Ga1.6
Ge1.8
As2.0
Se2.4
Br2.8
Rb 0.8
Sr1.0
In1.7
Sn1.8
Sb1.9
Te2.1
I2.5
Cs 0.7
Ba0.9
Tl1.8
Pb1.9
Bi1.9
VALENCE ELECTRONS TREND
Let’s look at Bohr Models…
http://www.chemicalelements.com/show/electronconfig.html
Valence Electrons Write on your PT
TREND: Valence Electrons# of valence electrons increases from 1-8 as you go left to right
Using Graphs toUnderstand
the Relationship Between
Atomic Radius andElectronegativity
GROUP 1H + Alkali
Metals
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)
0
0.5
1
1.5
2
2.5
0 1 2 3 4 5 6 7 8
Element
Ele
ctro
neg
ativ
ity
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) PERIOD 1Li - Ne
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
ATOMIC RADIUSTREND
Rank Small to Large: Cs, Ga, P, Rn
ELECTRONEGATIVITY
TREND
Rank Small to Large: Mg, Sr, Be, Ra
Why is this relationship true?
vs.
LARGE EN=
SMALL AR
LARGE AR=
SMALL EN
Work Time
Work on worksheet from Ms. Stroh
Exit Question
1. Draw the Bohr model for Carbon (C).
2. Which element has the largest electronegativity: Ag, Cu, Hg, or Zn?
HOMEWORK:ATOMIC TRENDS WORKSHEET