Do Now Work silently. Raise hand to ask Ms. Hughes anything. 1.Describe Thomson’s atomic model....

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

-

-

- -+

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)

-

-

- -

++

+ +

-

-

-

-

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?