NEW OPENER #1 - FRIDAY, SEPT. 7, 2012 Pick up computer but don’t turn on yet. Write in a sentence or complete.
Download ReportTranscript NEW OPENER #1 - FRIDAY, SEPT. 7, 2012 Pick up computer but don’t turn on yet. Write in a sentence or complete.
NEW OPENER #1 - FRIDAY, SEPT. 7, 2012
Pick up computer but don’t turn on yet.
Write in a sentence or complete statement.
1. What makes up an element?
2. What are 3 subatomic particles of the atom and what charge do these particles have?
3. Identify 3 scientists that you remember who worked with the development of atomic theory.
CW: Notes 3.1-3.2
CW: TIMELINE ACTIVITY with 1 PARTNER & Chemthink if time.
If absent, test should be made up after school (1.5 hours approximate time needed to make up.) We turned in openers, Bingo, mini-lab (milk&oil),
computer game sheet, notes packet ch.1-2 (keep if you
need to still take test to study with.)
Copyright © by Holt, Rinehart and Winston. All rights reserved.
ARK STANDARDS
pg. 72-76 pg. 67-69, 72-76, ch. 4: 97-103, 104-106
Copyright © by Holt, Rinehart and Winston. All rights reserved.
ARK STANDARDS
pa pg. 72-76 pg. 75-76 pg. 77-79 pg. 81-82
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 3
Section 2 The Structure of the Atom
Lesson Starter
• Even though the two shapes look different, the characteristics of the various parts that compose them are the same.
• The same is true with the atom.
• Though atoms of different elements display different properties, isolated subatomic particles have the same properties.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 3
Section 2 The Structure of the Atom
Objectives
• Summarize the observed properties of cathode rays that led to the discovery of the electron.
• Summarize the experiment carried out by Rutherford and his co-workers that led to the discovery of the nucleus.
• List the properties of protons, neutrons, and electrons.
• Define atom.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 3
Section 2 The Structure of the Atom
The Structure of the Atom
• An atom is the smallest particle of an element that retains the chemical properties of that element.
• The nucleus is a very small region located at the center of an atom.
• The nucleus is made up of at least one positively charged particle called a proton and usually one or more neutral particles called neutrons .
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 3
Section 2 The Structure of the Atom
The Structure of the Atom, continued
• Surrounding the nucleus is a region occupied by negatively charged particles called electrons .
• Protons, neutrons, and electrons are often referred to as subatomic particles .
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Chapter 3 Atom
Visual Concepts QuickTime™ and a Sorenson Video 3 decompressor are needed to see this picture.
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Chapter 3 Parts of the Atom
Visual Concepts Click below to watch the Visual Concept.
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3.2
Structure of the Nuclear Atom
Cathode-ray tubes are found in TVs, computer monitors, and many other devices with electronic displays. © Copyright Pearson Prentice Hall 10 Slide of 18 End Show
3.2
Structure of the Nuclear Atom > Subatomic Particles Electrons In 1897, the English physicist J. J. Thomson (1856 –1940) discovered the electron. Electrons are negatively charged subatomic particles.
© Copyright Pearson Prentice Hall 11 Slide of 25 End Show
Chapter 3
Section 2 The Structure of the Atom
Discovery of the Electron
Cathode Rays and Electrons • Experiments in the late 1800s showed that cathode rays were composed of negatively charged particles.
• These particles were named electrons .
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3.2
Structure of the Nuclear Atom > Subatomic Particles Thomson performed experiments that involved passing electric current through gases at low pressure. The result was a glowing beam, or cathode ray, that traveled from the cathode to the anode.
© Copyright Pearson Prentice Hall 13 Slide of 25 End Show
Chapter 3
Visual Concepts
Thomson’s Cathode-Ray Tube Experiment
Click below to watch the Visual Concept.
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3.2
Structure of the Nuclear Atom Cathode Ray Tube > Subatomic Particles QuickTime™ and a decompressor are needed to see this picture.
© Copyright Pearson Prentice Hall 15 Slide of 25 End Show
3.2
Structure of the Nuclear Atom > Subatomic Particles A cathode ray is deflected by a magnet.
QuickTime™ and a decompressor are needed to see this picture.
16 Slide of 25 End Show © Copyright Pearson Prentice Hall
3.2
Structure of the Nuclear Atom > Subatomic Particles A cathode ray is deflected by electrically charged plates.
© Copyright Pearson Prentice Hall 17 Slide of 25 End Show
3.2
Structure of the Nuclear Atom > Subatomic Particles Thomson concluded that a cathode ray is a stream of electrons. Electrons are parts of the atoms of all elements.
© Copyright Pearson Prentice Hall 18 Slide of 25 End Show
Chapter 3
Section 2 The Structure of the Atom
Discovery of the Electron, continued
Charge and Mass of the Electron • Joseph John Thomson’s cathode-ray tube experiments measured the charge-to-mass ratio of an electron.
• Robert A. Millikan’s oil drop experiment measured the charge of an electron.
• With this information, scientists were able to determine the mass of an electron. (Teacher note pg. 73)
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Chapter 3
Visual Concepts
Millikan’s Oil Drop Experiment
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Chapter 3
Section 2 The Structure of the Atom
Discovery of the Electron, continued
Charge and Mass of the Electron • The electron is 1/1837 times the mass of a hydrogen atom. • Since the electron is so small, atoms must contain other particles that account for most of their mass.
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3.2 Studying Atoms
Thomson’s Model of the Atom
• Thomson’s model is called the “plum pudding” model. Today, it might be called the “chocolate chip ice cream ” model. • The chips represent negatively charged electrons, which are spread evenly through a mass of positively charged matter — the vanilla ice cream. Thus, the pudding has a positive charge and the plums represent the negative charge spread evenly throughout.
3.2
Structure of the Nuclear Atom > The Atomic Nucleus J.J. Thompson and others supposed the atom was filled with positively charged material and the electrons were evenly distributed throughout.
This model of the atom turned out to be short lived, however, due to the work of Ernest Rutherford (1871 –1937).
23 Slide of 25 End Show © Copyright Pearson Prentice Hall
3.2
Structure of the Nuclear Atom > The Atomic Nucleus Rutherford’s Gold-Foil Experiment In 1911, Rutherford and his coworkers at the University of Manchester, England, directed a narrow beam of alpha particles at a very thin sheet of gold foil. Ernest Rutherford’s Portrait © Copyright Pearson Prentice Hall 24 Slide of 25 End Show
3.2
Structure of the Nuclear Atom > The Atomic Nucleus BE SURE TO CLICK BELOW Rutherford’s Gold-Foil Experiment Click here for Gold-Foil Animation Quick Activity Click for Gold-Foil Animation Quick Activity © Copyright Pearson Prentice Hall 25 Slide of 25 End Show
3.2
Structure of the Nuclear Atom > The Atomic Nucleus Alpha particles scatter from the gold foil.
© Copyright Pearson Prentice Hall 26 Slide of 25 End Show
3.2
Structure of the Nuclear Atom > The Atomic Nucleus The Rutherford Atomic Model Rutherford concluded that the atom is mostly empty space. All the positive charge and almost all of the mass are concentrated in a small region called the nucleus. The nucleus is the tiny central core of an atom and is composed of protons and neutrons.
27 Slide of 25 End Show © Copyright Pearson Prentice Hall
3.2
Structure of the Nuclear Atom > The Atomic Nucleus In the nuclear atom, the protons and neutrons are located in the nucleus. The electrons are distributed around the nucleus and occupy almost all the volume of the atom.
28 Slide of 25 End Show © Copyright Pearson Prentice Hall
Chapter 3
Section 2 The Structure of the Atom
Discovery of the Atomic Nucleus
• More detail of the atom’s structure was provided in 1911 by Ernest Rutherford and his associates Hans Geiger and Ernest Marsden.
• The results of their gold foil experiment led to the discovery of a very densely packed bundle of matter with a positive electric charge.
• Rutherford called this positive bundle of matter the nucleus .
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Chapter 3
Section 2 The Structure of the Atom Gold Foil Experiment QuickTime™ and a decompressor are needed to see this picture.
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Chapter 3
Section 2 The Structure of the Atom Gold Foil Experiment on the Atomic Level
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Chapter 3
Visual Concepts
Rutherford’s Gold Foil Experiment
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Chapter 3
Section 2 The Structure of the Atom
Composition of the Atomic Nucleus
• Except for the nucleus of the simplest type of hydrogen atom, all atomic nuclei are made of protons and neutrons.
• The nucleus of an atom is made up of protons that have a positive charge and neutrons that have a neutral charge. • The charge of the nucleus is positive. • Atoms are electrically neutral because they contain equal numbers of protons and electrons.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
3.2
Structure of the Nuclear Atom > Subatomic Particles In 1932, the English physicist James Chadwick (1891 –1974) confirmed the existence of yet another subatomic particle: the neutron by bombarding Be atoms with alpha rays and using paraffin wax. Neutrons are subatomic particles with no charge but with a mass nearly equal to that of a proton and are found in the nucleus of the atom.
• A neutron is electrically neutral and has ability to penetrate lead and other substances more because it is not reflected by any other charge.
© Copyright Pearson Prentice Hall 34 Slide of 25 End Show
3.2
Structure of the Nuclear Atom > Subatomic Particles Table 4.1 summarizes the properties of electrons, protons, and neutrons.
© Copyright Pearson Prentice Hall 35 Slide of 25 End Show
Structure of the Nuclear Atom > Model of Atom nucleus © Copyright Pearson Prentice Hall Slide of 25 End Show
Chapter 3
Section 2 The Structure of the Atom
Composition of the Atomic Nucleus, continued
• The nuclei of atoms of different elements differ in their number of protons and therefore in the amount of positive charge they possess.
• Thus, the number of protons determines that atom’s identity.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 3
Section 2 The Structure of the Atom
Composition of the Atomic Nucleus, continued
Forces in the Nucleus • When two protons are extremely close to each other, there is a strong attraction between them.
• A similar attraction exists when neutrons are very close to each other or when protons and neutrons are very close together.
• The short-range proton-neutron, proton-proton, and neutron-neutron forces that hold the nuclear particles together are referred to as nuclear forces .
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Chapter 3 Nuclear Forces
Visual Concepts Click below to watch the Visual Concept.
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Chapter 3 Forces in Atoms
Visual Concepts Click below to watch the Visual Concept.
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Chapter 3
Section 2 The Structure of the Atom
Composition of the Atomic Nucleus, continued The region occupied by electrons is called the electron cloud. It makes up the greatest part of the atom.
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Chapter 3
Section 2 The Structure of the Atom Properties of Subatomic Particles
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3.2
Defining the Atom > Sizing up the Atom
Sizing up the Atom
What instruments are used to observe individual atoms?
© Copyright Pearson Prentice Hall 43 Slide of 18 End Show
3.2
Defining the Atom > Sizing up the Atom Despite their small size, individual atoms are observable with instruments such as scanning tunneling microscopes.
© Copyright Pearson Prentice Hall 44 Slide of 18 End Show
3.2
Defining the Atom > Sizing up the Atom Iron Atoms Seen Through a Scanning Tunneling Microscope © Copyright Pearson Prentice Hall 45 Slide of 18 End Show
Chapter 3
Section 2 The Structure of the Atom
The Sizes of Atoms
• The radius of an atom is the distance from the center of the nucleus to the outer portion of its electron cloud.
• Because atomic radii are so small, they are expressed using a unit that is more convenient for the sizes of atoms.
• This unit is the picometer, pm.
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3.2
Section Quiz
Assess students’ understanding of the concepts in Section 3.2.
Continue to: Launch: -or Section Quiz Slide of 18 End Show © Copyright Pearson Prentice Hall
3.2
Section Quiz
1. Which of the following is NOT an example of a subatomic particle?
a. proton b. molecule c. electron d. neutron Slide of 18 End Show © Copyright Pearson Prentice Hall
3.2
Section Quiz
2. The nucleus of an atom consists of a. electrons only.
b. protons only.
c. protons and neutrons.
d. electrons and neutrons.
© Copyright Pearson Prentice Hall Slide of 18 End Show
3.2
Section Quiz
3. Most of the volume of the atom is occupied by the a. electrons.
b. neutrons.
c. protons and neutrons.
d. protons.
Slide of 18 End Show © Copyright Pearson Prentice Hall
3.2
Section Quiz
4. The ancient Greek philosopher credited with suggesting all matter is made of indivisible atoms is a. Plato.
b. Aristotle.
c. Democritus.
d. Socrates.
Slide of 18 End Show © Copyright Pearson Prentice Hall
3.2
Section Quiz
5. Dalton's atomic theory improved earlier atomic theory by a. teaching that all matter is composed of tiny particles called atoms.
b. theorizing that all atoms of the same element are identical.
c. using experimental methods to establish a scientific theory.
d. not relating atoms to chemical change.
Slide of 18 End Show © Copyright Pearson Prentice Hall
3.2
Section Quiz
6. Individual atoms are observable with a. the naked eye.
b. a magnifying glass.
c. a light microscope.
d. a scanning tunneling microscope.
© Copyright Pearson Prentice Hall Slide of 18 End Show
Online Self-Check Quiz
Complete the online 3.2 Quiz and record answers. Ask if you have any questions about your answers. click here for online Quiz 3.2
(10 questions) You must be in the “Play mode” for the slideshow for hyperlink to work.
Slide of 25 End Show © Copyright Pearson Prentice Hall
SECTION 3.2
END OF 3.2 PRESENTATION © Copyright Pearson Prentice Hall Slide of 18 End Show