do now work silently. raise hand to ask ms. hughes anything. 1.describe thomson’s atomic model....
TRANSCRIPT
Do NowWork silently. Raise hand to ask Ms.
Hughes anything.
1. Describe Thomson’s atomic model.
2. Describe Dalton’s atomic model.
Announcements
• Unit 3 test next Friday
• If you have not taken 2 chemistry tests yet this semester, see me after to arrange a make up
• Also, come in for quick tutoring, then RETAKE GLEs for a GRADE BOOST
Mystery Element#1: Too little of this element in the
body causes osteoporosis.
#2: You can get this element from drinking milk
#3: It is good for your bones!
Numero Cinco! - R. A. Millikan
• Experiment: Millikan Oil Drop Experiment
• When: 1909
• Where: U.S.A!!!!
Millikan’s Oil Drop Experiment
Millikan!
• Sprayed oil drops• Drops fell between magnetic plates• Drops radiated to give them negative
charge• Measured how fast they fell to find charge
and mass• Gravity pulls them down…But since
opposite charges attract and likes repel• The magnetic plates pushed the drops up
Millikan’s Calculations – Whoa!
What were Millikan’s conclusions?
I have most accurately measured the charge
of an electron:
-1.59 x 10-19 Coulombs
What were Millikan’s conclusions?
I have also most
accurately measured
the mass of an electron:9.109 x 10-
31kg
What were Millikan’s conclusions?
The electron is
really really
small and has a
negative charge
Numero Seis! - Ernest Rutherford
• Experiment: Gold Foil Experiment
• When: 1910• Where: Montreal
Gold Foil Experiment Explained
• Alpha helium particles were shot through a piece of gold foil
– Think aluminum foil but thinner and made out of gold!
• Alpha helium particles are 8000 times more massive (bigger) than electrons
• Rutherford thought alpha particles would knock electrons out of the way, since atom is only electrons in sea of positive charge
http://micro.magnet.fsu.edu/electromag/java/rutherford/
Remember! This is the current model of the atom (Thanks to
Thomson)
More History
Ernie’s (Rutherford) Big AdventureErnie’s (Rutherford) Big Adventure
Thin Sheet of GoldAtoms
What were Rutherford’s conclusions?
• 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
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- -+
What were Rutherford’s conclusions?
•Discovered the nucleus, a concentrated mass with positive protons!•Nucleus is in the center of the atom•The atom is mostly empty space•Electrons orbit around nucleus
What’s this empty space idea?
• The atom is mostly empty space!
• The nucleus is TINY compared to the size of the entire atom!
• Called “the planetary model” because electrons orbit like planets in empty space
Relative Size of Nucleus to the Atom
Rutherford Simulation
• Let’s do this thing OURSELVES…but without radioactive particles
James Chadwick
• Experiment: Beryllium Foil Experiment
• When: 1932• Where:
Cambridge (England)
Beryllium foil experiment
• Similar to gold foil experiment
• Shot alpha particles at beryllium foil
• Noticed neutral radiation coming out
• That neutral radiation could knock protons out of the way
• Therefore, heavy neutral particles exist in the atom
What were Chadwick’s conclusions?
Neutral radiation emitted; therefore,
the nucleus contains another
subatomic particle called the
neutron (has a neutral charge)
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- -
++
+ +
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-
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NUCLEUS
NEUTRONELECTRON
PROTON
Picture History
Draw a picture history of the atomic model on the timeline
RAFT - Independent Work TimeDue Friday
R = RolePretend to be either Dalton, Thomson, Rutherford.
A = AudienceYou are writing to the theorist directly before you.
F = FormatNewspaper article, Letter or Rap
T = TopicDetails of your discovery, how you know it is true,
and why it is better than the guy before you.YOU HAVE “WORKED” HARD…DEFEND YOUR
RESEARCH!
Assignment: RAFT
• Option 1: Rap
• Role: An atomic Theorist
• Audience: Writing to another atomic theorist
• Form: an appropriate rap
• Topic: Why your theory and model is better than theirs
+3 points for presenting on Friday
Assignment: RAFT
• Option 2: Polite, Formal Letter or Newspaper article
• Role: An atomic Theorist• Audience: Writing to another atomic
theorist• Form: a formal letter• Topic: Politely stating why your theory and
model proves theirs wrong +3 points for presenting on Friday
Assignment: RAFTThings to Include
• Personal information about both theorists - where they’re from, physical appearance, etc.
• All necessary facts about both theories or models
• How the theory is better than the one that came before it
3 Subatomic Particles
• Protons• Neutrons• Electrons
THE PROTON
p+
• Fat (heavy)
• Positive (charge)
• Doesn’t move (lazy)
THE NEUTRON
N°
• Fat (heavy)
• Neutral (charge)
• Doesn’t move (lazy)
THE ELECTRON• Skinny (very light)
• Negative (charge)
• Moves a lot (runs around)
e-
Review of Subatomic Particles
Subatomic Particle
Location Mass Charge
Protons
Neutrons
Electrons
NUCLEUS
NUCLEUSOUTSIDE NUCLEU
S
1.6726 x 10-27 kg
1.6749 x 10-27 kg
9.1094 x 10-
31 kg
1+NEUTRAL
1-
Review: Subatomic Particles
e-
NP+
Exit Slip
1. What experiment did Rutherford use to? What did he discover?
2. How did Rutherford change the atomic model?
• Hw: Make it a QUALITY short answer– What are the three subatomic particles and
how did we discover each? Name the experiment and give a brief description.
• Top ten: how’d we do?