6A 1 SCIENTISTS.notebook

1

October 27, 2015

Nov 4­10:28 AM

Models of the AtomThe Nature of Matter Textbook

Inside the Atom

Lesson objectives Teachers' notes

1) Explain how scientists discovered particles of an atom.

2) Explain how today's model of the atom was developed.

3) Describe the structure of the nuclear atom.

Oct 20­8:57 AM

Oct 20­3:11 PM

6A 1 SCIENTISTS.notebook

2

October 27, 2015

Oct 22­3:08 PM

Oct 20­9:05 AM

Oct 26­8:52 AM

6A 1 SCIENTISTS.notebook

3

October 27, 2015

Oct 26­8:52 AM

Oct 26­8:52 AM

Oct 26­8:52 AM

6A 1 SCIENTISTS.notebook

4

October 27, 2015

Nov 4­10:28 AM

Teachers' notesLesson objectives

Subject:Topic:

Grade(s):Prior knowledge:

The Nature of MatterInside the Atom ­ Scientists6Knowledge of atoms

Lesson notes:

Learning Target:

• Students will be able to identify two models of the atom and their creators.

Bell Work:

• Look through the periodic table. What elements to do you recognize? Make a list and identify where you find them.

Mar 19­7:45 AM

Ernest Rutherford discovered the current model of the atom.

J. J. Thomson discovered the electron.

Crookes i

nvented

the Cathod

e­Ray

tube exam

ining

positive a

nd

negative p

articles.

John Dalton combined the idea of elements with Greek theory of the atom.

Models of the AtomThe Nature of Matter

Inside the Atom

Why are these men

important to Science?

Mar 19­7:45 AM

Combined Greek theory of the Atom with the idea of elements.

John Dalton

Propose ideas about matter:

1) Matter is made up of atoms.

2) Atoms cannot be divided into smaller pieces.

3) All atoms of an element are exactly alike.

4) Different elements are made of different kinds of atoms.

6A 1 SCIENTISTS.notebook

5

October 27, 2015

Oct 15­1:26 PM

John Dalton= Ideas about Matter

1. Matter is made up of atoms

2. Atoms cannot be divided smaller

3. All atoms of an element are exactly alike

4. Different elements are made of different kinds of atoms

Mar 19­7:45 AM

John Dalton

Dalton imagined an atom as a hard sphere that was the same throughout.

Mar 19­7:45 AM

William Crookes

Crookes also tested theories about atoms.He completed his experiments using a glass tube. This was know as his Cathode Ray Tube or CRT.

6A 1 SCIENTISTS.notebook

6

October 27, 2015

Oct 15­1:26 PM

1870 ­ William Crookes

Experiments with a glass tube; cathode ray tube.

Electrodes (metal pieces) were connected to wires

CRT

Anode

Electrode

Positive charge

Negative charge

Jun 24­9:34 AM

How did Crookes make the Cathode Ray Tube work?

Cathode creates a negative charge.

Anode creates positive charge.

When a battery is connected with the glass tube, a green glow appeared. A shadow of the object appeared at the opposite end of the tube at the anode. Something was traveling from the cathode to the anode. The cross was getting in the way!

Shadow which was created.

Mar 19­7:45 AM

J. J. Thompson

J. J. Thompson continues Crookes's discovery of a beam of light with the CRT. He placed magnets beside the beam of light, and the beam bent. Thompson concluded that the light was not really a light at all. It was charged particles. He also concluded that the particles in the tube were negatively charged called electrons. There was now evidence that particles smaller than the atom exists. Click on the links below to see examples and learn more.

6A 1 SCIENTISTS.notebook

7

October 27, 2015

Nov 2­12:26 PM

Draw a model of Thomson's and Rutherford's idea of the atom.

Oct 19­3:07 PM

Oct 15­1:26 PM

1897 ­ JJ Thompson

Light can be bent by a magnet; therefore beam is made up of charged particles

Negatively charged particles

Charged

Particles

Electrons

6A 1 SCIENTISTS.notebook

8

October 27, 2015

Mar 19­7:45 AM

Ernst Rutherford

Ernest Rutherford experimented with Thompson's findings. Rutherford wanted to see what would happen when they fired fast moving, positively charged bits of matter called alpha particles at gold (a form of metal). Rutherford thought that the particles would go straight through the gold. His experiment did not go as planned and some of the particles bounced back. He hypothesized that most charges are crammed into a small region of space at the center of the atom called the nucleus.

Mar 19­7:45 AM

Today's Model

With Rutherford's findings, a new model of the atom developed. Though, some of the data did not make sense. According to Rutherford's model the only other particle in the atom was a proton. That meant that the mass of the atom should have been equal to the mass of the protons. This did not add up because the mass of most atoms was at least twice as great as the mass of its protons. The scientists were puzzled. Where did the extra mass come from? It was thought that the extra mass came from another particle in the nucleus. This particle would be called a neutron, and had the same mass at the proton. The particle was neutral.

Oct 15­1:26 PM

1906 ­ Ernest RutherfordFailed experiment results in new hypothesis: the mass of the atom & its positively charged particles are located in the nucleus.

Negatively charged particles have almost no mass.

Proton

Electrons

Extra mass accounted for as the neutron is discovered; has no charge so is neutral.

Neutron

6A 1 SCIENTISTS.notebook

9

October 27, 2015

Mar 19­7:45 AM

Today's Model

After the neutron was discovered, Neil Bohr's calculations showed that it was impossible to know where the electrons were located in a particular time. This inspired more research. New theories of the atomic model were developed. Scientists believed that since electrons were impossible to locate, then they must be traveling in the region around the nucleus called the electron cloud. They also were more likely to be traveling closer to the nucleus since the electrons are attracted to the positive charges of the protons.

Oct 15­1:26 PM

Niels BohrElectrons do NOT orbit the nucleus; they are in constant unpredictable motion

Electron

Movement

Electron

Cloud

The region around the nucleus where the electrons exist.

Mar 19­7:45 AM

electrons

Protons

Let's Reveal and Review!

Erase and reveal today's model of the atom with it's important parts.

Neutrons

6A 1 SCIENTISTS.notebook

10

October 27, 2015

Oct 15­12:54 PM

Nov 4­10:28 AM

Models of the AtomThe Nature of Matter Textbook

Inside the Atom

Lesson objectives Teachers' notes

EXIT TICKET...

Go back to page 8B and answer questions 1 ­ 3 again.

Is your answer different?

Oct 15­1:40 PM

Learning Target:

• Students will be able to identify two models of the atom and their creators.

DID WE MEET OUR LEARNING TARGET?

6A 1 SCIENTISTS.notebook

11

October 27, 2015

Jun 26­5:00 PM

Oct 16­9:11 PM