4.2 The Structure of an Atom
Opener #4 - Wed., April 14, 2010
Write in complete sentences.
Answer Sect. 4.2 pg. 112 #4-9.
CW: Handout on atomic number & atomic mass...
CW: Complete all research of element/atom; be sure to research at least 3 websites
and become an expert on your element... Work on your interactive poster from
edu.Glogster.com site using your nickname and password that I gave you. You will
include the information like your handout along with your slogan/poem/acrostic plus
remember you must have at least 1 picture and 1 video plus your oral presentation
which may be done via a keynote with voice override, pictures with voice, live
video(iMovie) or other approved method to present. You will need to include all basic
facts from your research page plus point out your specific parts of your model such as
the number of electrons, protons and neutrons along with their respective charges
number, and location; make sure I know what they are in the model. You will decorate
up your poster and publish and make public.
You should include interesting facts, why the element is important, how it is used,
common compounds where it might be found, etc.
4.3 Modern Atomic Theory
Opener #3 - Tuesday - April 13, 2010 -- Use complete sentences.
Answer questions Section 4.2 pg. 112 #1-3.
CW: Element Name & Symbols QUIZ...
CW: Notes 4.3
CW: Work on interactive poster portion along with phrase/slogan/acrostic
on your Glogster account...
HW: 3-D atom project due tomorrow! We will start video of presentation
tomorrow and Thursday to try to complete Glogster interactive site......
4.3 Modern Atomic Theory
Monday, October 25, 2010
OPENER #6
1. Which characteristic of an atom always varies among atoms of different elements?
2. How do we name an isotope? How are isotopes of an element different from one
another?
3. What does the atomic number tell you about a neutral atom?
CW: Notes “4.3” ....
CW: Completing Interactive Poster - PAGES and starting video recording of
presentation.... if time allows...
TEST Unit 4 (ch.4-5 PAP) next Tuesday, Nov. 2nd...
QUIZ this week over knowing how to determine # of protons, electrons, & neutrons,
atomic # and atomic mass with isotopes of elements... (like chart in notes....)
Element/Symbols QUIZ - You may retake the quiz one time this week only to replace
your grade. Retakes do NOT count toward Pizza party, however. You need to know the
element names and symbols to help you in the next unit which gets a little tougher.
4.3 Modern Atomic Theory
Go over how you will start creating your video presentation portion if you are ready for
that stage. We are using PAGES application for the interactive POSTER instead of
Glogster now... but all the requirements remain the same...
*To make an iMovie... (easiest method)
*To make a keynote presentation with audio/video + pictures... You have to have
everything set up before you do audio override or do sounds for each slide and place
on each slide using audio created with iMovie...
REQUIREMENTS: explaining each part of your model (name, symbol, atomic number,
show where and how many protons, neutrons, and electrons) - Give the charges of
each as you explain, tell important and interesting facts about your element research,
and share your poem/acrostic/slogan/song you created. You may also use texts with
your voice portions, and you may include video in the background if you choose.
photobooth can be used for taking still pictures of atom project...
4.3 Modern Atomic Theory
Have you ever wondered what
produces the different colors in a
fireworks display?
Certain compounds will produce
certain colors of light when they
are heated. Compounds
containing the element strontium
produce red light. Compounds
containing barium produce green
light.
Click below for video clip!
Then click on “VIEW”
Fireworks! Making Color video clip
Chapter 4
Section 1 Atomic Structure
Bohr Model of the Atom
Click below to watch the Visual Concept.
http://my.hrw.com/sh/hk6_00303
90966/student/ch04/sec01/vc02/h
Visual Concept
k604_01_v02fs.htm
Chapter menu
Resources
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4.3 Modern Atomic Theory
Bohr’s Model of the Atom
As did Rutherford's atomic model, Bohr’s atomic
model had a nucleus surrounded by a large
volume of space. In Bohr’s model, he focused on
the electrons and their arrangement.
In Bohr’s model, electrons move with constant
speed in fixed orbits around the nucleus, like
planets around a sun. Each electron in an atom
has a specific amount of energy.
4.3 Modern Atomic Theory
Bohr’s Model of the Atom
Energy Levels
• The possible energies that electrons in an atom
can have are called energy levels.
• An electron cannot exist between energy levels.
4.3 Modern Atomic Theory
Bohr’s Model of the Atom
An electron in an atom can move from one
energy level to another when the atom gains
or loses energy.
Electron
Electrons gain or
lose energy when
they move
between fixed
energy levels
Nucleus
Bohr Model
Chapter 4
Section 1 Atomic Structure
Building Model
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Chapter 4
Section 1 Atomic Structure
Electron Energy Levels
Click below to watch the Visual Concept.
http://my.hrw.com/sh/hk6_0030390966/stu
Visual Concept
dent/ch04/sec01/vc03/hk604_01_v03fs.ht
m
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
4.2 The Structure of an Atom
Valence Electrons...
QuickTime™ and a
decompressor
are needed to see this picture.
4.3 Modern Atomic Theory
Bohr’s Model of the Atom
The movement of electrons between energy
levels explains the light you see when fireworks
explode.
• Heat produced such as in fireworks is absorbed by
electrons and moves to a higher energy level.
• When those electrons move back to lower energy
levels, they release energy. Some of that energy is
released as visible light.
• Different elements emit different colors of light
because no two elements have the same set of
energy levels.
• example: FLAME TEST LAB
4.3 Modern Atomic Theory
Electron Cloud Model
Bohr’s model was was correct in assigning
energy levels to electrons, but he was in correct in
saying that electrons moved in fixed orbits like
planets in a solar system.
Today, scientists use probability when trying to
predict the locations and motions of electrons in
atoms.
An electron cloud is a visual model of the most
likely locations for electrons in an atom.
The cloud is denser where the probability of
finding electrons is high.
Chapter 4
Section 1 Atomic Structure
Models of the Atom, continued
• Electrons act more like waves.
• By 1925, Bohr’s model of the atom no longer
explained electron behavior.
• A new model was proposed, in which electrons
behave more like waves on a vibrating string than
like particles.
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4.3 Modern Atomic Theory
Electron Cloud Model
The electron cloud model replaced Bohr's vision
of electrons moving in predictable paths.
The electron cloud is a
visual model of the
probable locations of
electrons in an atom.
The probability of finding
an electron is higher in
the denser regions of the
cloud.
The nucleus
contains protons
and neutrons
Electron Cloud Model
4.3 Modern Atomic Theory
Electron Cloud Model
The photographs below provide an analogy for an
electron cloud. When the propeller of an airplane
is at rest, you can see the location of the blades.
When the propeller is moving, you see only a blur
that is similar to a drawing of an electron cloud.
Chapter 4
Section 1 Atomic Structure
Models of the Atom, continued
• An electron’s exact location cannot be determined.
• It is impossible to determine both the exact
location of an electron in an atom and the
electron’s speed and direction.
• The best scientists can do is calculate the chance
of finding an electron in a certain place within
an atom.
Chapter menu
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Copyright © by Holt, Rinehart and Winston. All rights reserved.
4.3 Modern Atomic Theory
Electron Cloud Model
What model do scientists use to describe
how electrons behave in atoms?
An orbital is a region of space around the
nucleus where an electron is likely to be found.
The electron cloud represents all the orbitals in
an atom.
Click below to see the visual on orbital.
An electron cloud is a good approximation of
how electrons behave in their orbitals.
4.3 Modern Atomic Theory
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
CLICK BELOW FOR LINK TO PLAY IF IT DOESN’T START PLAYING.
http://my.hrw.com/sh/hk6_0030390966/student/ch04/se
c01/vc05/hk604_01_v05fs.htm
4.3 Modern Atomic Theory
Electron Cloud Model
For an analogy to the concept of an orbital,
imagine a map of your school. Mark your exact
location with a dot once every 10 minutes over a
period of one week. The dots on your map are a
model of your “orbital.” They describe your most
likely locations.
• The places you visit the most would have the highest
concentration of dots.
• The places you visit the least would have the lowest
concentration of dots.
4.3 Modern Atomic Theory
Electron Cloud Model
In the first energy level, an electron has the
least energy—the lowest energy level—has
only one orbital. Higher energy levels have
more than one orbital.
Use this
table to help
answer your
question... about
how many
electrons are
in each orbital...
4.3 Modern Atomic Theory
•The maximum number of electrons in an energy level is
twice the number of orbitals.
•Each orbital can contain 2 electrons.
Chapter 4
Section 1 Atomic Structure
s - orbital
Click below to watch the Visual Concept.
•http://my.hrw.com/sh/hk6_003
0390966/student/ch04/sec01/v
Visual Concept
c06/hk604_01_v06fs.htm
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 4
Section 1 Atomic Structure
Models of the Atom, continued
• Electrons are found in orbitals within energy levels.
• An orbital is a region in an atom where there is a high
probability of finding electrons.
• An s orbital is shaped like a sphere:
• It can hold 2 electrons.
Chapter menu
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Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 4
Section 1 Atomic Structure
p - orbitals
Click below to watch the Visual Concept.
http://my.hrw.com/sh/hk6_003039
Visual Concept
0966/student/ch04/sec01/vc07/hk6
04_01_v07fs.htm
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
p-orbital, d-orbital, & f-orbital
•p orbital – shape is dumbell, has 3 different axis orientations,
each p orbital can hold two electrons, and the three p orbitals can
hold a total of six electrons.
•d orbital – complex lobes, 5 possible d orbitals, each orbital can
hold two electrons, the five possible d orbitals can hold a total
of 10 electrons.
•f orbital – complex lobes, 7 possible f orbitals, each orbital can
hold two electrons, the seven possible f orbitals can hold a total
of 14 electrons.
Chapter menu
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Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 4
Section 1 Atomic Structure
Models of the Atom, continued
• Every atom has between one and eight
valence electrons.
• Valence electrons are found in the outermost
shell of an atom and determine the atom’s
chemical properties.
• Valence electrons are the electrons in an atom
that participate in chemical bonding.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 4
Section 1 Atomic Structure
Valence Electrons
Click below to watch the Visual Concept.
http://my.hrw.com/sh/hk6_0030390966/s
Visual Concept
tudent/ch04/sec01/vc08/hk604_01_v08fs
.htm
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
4.3 Modern Atomic Theory
Electron Configurations
What is the most stable configuration of
electrons in an atom?
4.3 Modern Atomic Theory
Electron Configurations
An electron configuration is the arrangement of
electrons in the orbitals of an atom.
When all the electrons in an atom have the lowest
possible energies, the atom is said to be in its
ground state.
The most stable electron configuration is the
one in which the electrons are in orbitals with
the lowest possible energies.
4.3 Modern Atomic Theory
Electron Configurations
A lithium atom has three electrons.
• In the ground state, two of the lithium electrons are in
the orbital of the first energy level.
• The third electron is in an orbital of the second energy
level.
• If a lithium atom absorbs enough energy, one of its
electrons can move to an orbital with a higher energy.
• This configuration is referred to as an excited state. An
excited state is less stable than the ground state.
• Eventually, the electron that was promoted to a higher
energy level loses energy, and the atom returns to the
ground state. (ex. lithium atom)
4.3 Modern Atomic Theory
Electron Configurations
The ground state of a person is
on the floor. A gymnast on a
balance beam is like an atom in
an excited state—not very
stable.
When she dismounts, the
gymnast will return to a lower,
more stable energy level.
4.3 Modern Atomic Theory
Show visual concept with comparison between Thompson, Bohr, and Rutherford
quick summary... (Comparing models of atoms.)
http://my.hrw.com ch. 4 atomic model comparisons...
Click link below and then click on play to watch:
http://my.hrw.com/sh/hk6_0030390966/student/ch04/sec01/vc04/hk604_01_v04fs.
htm
4.3 Modern Atomic Theory
Assessment Questions - answer these
questions mentally & check your answer.
1. According to Bohr’s model of the atom, which of
the following can happen when an atom gains
energy?
a.
b.
c.
d.
An atom returns to its ground state.
A neutron can be changed into a proton.
A proton can move to a higher energy level.
An electron can move to a higher energy level.
4.3 Modern Atomic Theory
Assessment Questions
1. According to Bohr’s model of the atom, which of
the following can happen when an atom gains
energy?
a.
b.
c.
d.
An atom returns to its ground state.
A neutron can be changed into a proton.
A proton can move to a higher energy level.
An electron can move to a higher energy level.
ANS: D
4.3 Modern Atomic Theory
Assessment Questions
2. How does the modern atomic theory describe the
location of electrons in an atom?
a. Electrons move randomly in space around the nucleus.
b. Electrons can be described as a cloud based on
probable locations.
c. Electrons orbit the nucleus in the same way that planets
orbit the sun.
d. Electrons move in a spiral pattern if increasing distance
from the nucleus.
4.3 Modern Atomic Theory
Assessment Questions
2. How does the modern atomic theory describe the
location of electrons in an atom?
a. Electrons move randomly in space around the nucleus.
b. Electrons can be described as a cloud based on
probable locations.
c. Electrons orbit the nucleus in the same way that planets
orbit the sun.
d. Electrons move in a spiral pattern if increasing distance
from the nucleus.
ANS: B
4.3 Modern Atomic Theory
Assessment Questions
3. What is meant when an atom is said to be in its
ground state?
a. There is no net charge on the atom.
b. The number of protons equals the number of neutrons.
c. The atom’s electrons all have the lowest possible
energies.
d. It is the isotope with the least number of neutrons.
4.3 Modern Atomic Theory
Assessment Questions
3. What is meant when an atom is said to be in its
ground state?
a. There is no net charge on the atom.
b. The number of protons equals the number of neutrons.
c. The atom’s electrons all have the lowest possible
energies.
d. It is the isotope with the least number of neutrons.
ANS: C
4.3 Modern Atomic Theory
Note to me: Finish with 2nd part of Notes 4.2