Catalyst – January
49-21, 2011
FUN GRAPH
FRIDAY!!!
1. Describe what
happens to atomic
volume as atomic
weight increases.
2. What type of
graph is this?
3. Do Na, K, Rb,
and Cs have
anything in
common?
Today’s Agenda
Catalyst
 Quick Review of Day 1!
 Atomic Theory Part 2
 Atomic Facebook/Isotope Challenge!
 SCIENTIFIC SHOWDOWN: Andre vs.
Jordan
 Group of the Week and Tests Back
 Exit Question
HW: Unit 1 Resume

Today’s Objectives
SWBAT describe the evolution of
atomic theory from 1898 to present.
 SWBAT write a conclusion and
defend a theory using evidence.

2nd Period (58% of Class)
Unit 1 Masters (85% or above)
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Bethany Alumbaugh
Jordan Baye
Marissa DeQueant
Christopher Gordon
Spencer Gros
Frank Hyler
Josh Jackson
Tywanda Jacobs
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Casey Jones
Richielle Kelly
Karen Nguyen
Baily Payne (100!)
Phoebe Plaisance
Kyle Robichaux
Michael Tran
3rd Period (67% of Class)
Unit 1 Masters (85% or above)
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Kat Adams (100!)
Ja’Shion Alexander
Paula Datri
Gilberto Frutos
Robert Gaines
A’Lena Garrett
Destiny Gibson
Daniel Jackson
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Epiphany Johnson
Julia Lewin (100!)
Katelyn Lewis
Kendell Nabonne
Nadia Perrilliat
Jill Robinson
Carolina Torres
Victoria Zelaya
4th Period (43% of Class)
Unit 1 Masters (85% or above)
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Carlee Blackley
Darrell Chandler
Eugene Hollingshed
Shannon Malonson
Tarje Marks
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Gecoba Robinson
Gino Sanchez
William Smith
Centoria Turner
Adriona Watkins
Pop Quiz #3
1.
2.
3.
4.
5.
Define matter.
Fill in the blank: Matter is composed of tiny
particles called _________.
What particle did Thomson discover?
Who discovered the nucleus?
Fill in the blanks: Isotopes are atoms with the
same number of ________ but different numbers
of ________.
Quick Review

Democritus – 420 B.C. – First to think atoms exist


Dalton – 1808 – First REAL Atomic Theory


Not a theory – no proof
Based on scientific evidence
JJ Thompson – 1897 – Cathode Ray Experiment

Showed presence of small negative parts of atoms

These parts are called electrons
Implied presence of positive parts
 Showed atoms are NOT indivisible
 Developed Plum Pudding Model

Ernest Rutherford
Experiment: Gold
Foil Experiment
 Where: University of
Manchester
(England)
 When: 1909

Lil’ Ernie Rutherford on the Scene!

Rutherford shot positively charged alpha
particles at a very thin piece of gold foil
What Lil’ Ernie thought would happen…

If the Plum Pudding model was true, all of the
positively charged alpha particles would have gone
straight through the foil
What Actually Happened…

Almost all of the alpha particles went straight
through, but some were deflected
1
in 8000 of the particles was deflected
?
Simulation
http://phet.colorado.edu/simulations/si
ms.php?sim=Rutherford_Scattering
What do you think?
Pretend you are Rutherford
 As Rutherford, what conclusion would
you make based on the data from
the Gold Foil Experiment?

Hint: Positive repels
positive, negative
repels negative
=
Rutherford’s Conclusions
1.The atom is mostly empty space
through which negatively
charged electrons move
2.There is a tiny, dense region in
the center of the atom called the
nucleus (positively charged)
-
+
-
-
-
What’s this empty space idea?

The ratio of the size of
the nucleus to the
diameter of the orbits of
electrons can be
compared with placing a
marble in the middle of
a football stadium!
Relative Size of the Nucleus to the Atom
But this wasn’t all the way right!

Keeping in mind that opposites attract,
What
happens to the negatively charged
particles that are orbiting the positively
charged nucleus?
The Next Great Idea

In 1913, Niels Bohr considered the problem and
looked at new information
 Scientists
knew that moving electrons could create light
when they released energy
 They noticed each element only let out
certain wavelengths of light
 These
were called emission spectra
Analyzing the Spectra

Bohr inferred from the spectra that the electrons
could only exist certain distances from the nucleus
 They
could jump from level to another to create light
 But they could not exist between levels
Niels Bohr (1913)
•Rutherford’s nucleus idea is
good, but…
•Electrons orbit around the
nucleus in circular paths
called energy levels!
Valence electrons are
electrons on the
outer energy level!
NOT BOHR-ING
AT ALL!!!
But Someone Knew This Wasn’t Right
There were other emission line spectra for
larger atoms that did not fit the Bohr
Model…
 So in 1924 Erwin Schrödinger added a
new detail

Think
of the electrons as waves instead of
particles
Schrodinger’s Thinking
•If electrons are like waves,
then we don’t ever really
know where the electrons
are in the atom
•I will develop the idea of
ATOMIC ORBITALS!
Schrodinger’s
Atomic Orbitals
You will learn more
about this later!
Facebook/Isotope Challenge
You have the rest of class to work on this
worksheet
 Use the book to help you when needed
(especially on the back!)

Exit Question
1.
2.
What was Rutherford’s contribution to
atomic theory?
Describe one other game-changing
contribution to the atomic theory.
HOMEWORK: Unit 1 Resume
QUIZ NEXT TUESDAY!!!!