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Physical Science-Q4-dualnatureofelectrons

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Physical Science
Quarter 2 – Module 9:
Dual Nature of Electrons
CO_Q2_Physical Science SHS
Module 9
Physical Science
Alternative Delivery Mode
Quarter 2 – Module 9: Dual Nature of Electrons
First Edition, 2021
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Published by the Department of Education
Secretary: Leonor Magtolis Briones
Undersecretary: Diosdado M. San Antonio
Development Team of the Module
Writers: Marilou T. Flores and Ma. Clarinda N. Medequiso
Editors: Priscila D. Domino, Felipa A. Morada
Reviewers: Rogelio D. Canuel, Elmer C. Bobis, Felipa A. Morada,
Constancio T. Clopino, Jr.
Illustrator: Alvin G. Alejandro
Layout Artist: Pamela A. Lalusin, Elsie R. Reyes, Mary Grace L. Asa
Management Team: Francis Cesar B. Bringas
Job S. Zape, Jr.
Ramonito Elumbaring
Reicon C. Condes
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Catherine V. Maranan
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Physical Science
Quarter 2 – Module 9:
Dual Nature of Electrons
Introductory Message
This Self-Learning Module (SLM) is prepared so that you, our dear learners,
can continue your studies and learn while at home. Activities, questions, directions,
exercises, and discussions are carefully stated for you to understand each lesson.
Each SLM is composed of different parts. Each part shall guide you step-bystep as you discover and understand the lesson prepared for you.
Pre-tests are provided to measure your prior knowledge on lessons in each
SLM. This will tell you if you need to proceed on completing this module or if you
need to ask your facilitator or your teacher’s assistance for better understanding of
the lesson. At the end of each module, you need to answer the post-test to self-check
you’re learning. Answer keys are provided for each activity and test. We trust that
you will be honest in using these.
In addition to the material in the main text, Notes to the Teacher are also
provided to our facilitators and parents for strategies and reminders on how they can
best help you on your home-based learning.
Please use this module with care. Do not put unnecessary marks on any part
of this SLM. Use a separate sheet of paper in answering the exercises and tests. And
read the instructions carefully before performing each task.
If you have any questions in using this SLM or any difficulty in answering the
tasks in this module, do not hesitate to consult your teacher or facilitator.
Thank you.
ii
What I Need to Know
This module was designed and written with you in mind. It is here to help you master
the use of simple collision theory to explain the effects of concentration, temperature,
and particle size on the rate of reaction. The scope of this module permits it to be
used in many different learning situations. The language used recognizes the diverse
vocabulary level of students. The lessons are arranged to follow the standard
sequence of the course. But the order in which you read them can be changed to
correspond with the textbook you are now using.
The module is divided into two lessons, namely:
•
•
Lesson 1 – Is an Electron a Particle or a Wave?
Lesson 2 – Evidence of Wave-like Behavior of Electrons
After going through this module, you are expected to:
1. describe a particle and a wave,
2. identify key persons and their contribution in the development of the waveparticle duality theory.
3. perform an experiment to observe how electrons behave as a particle and a
wave, and
4. recognize the significance of understanding the dual behavior of electrons for
succeeding discoveries related to the nature of light.
What I Know
Directions: Choose the letter of the best answer. Write the chosen letter on a separate
sheet of paper.
1. A minute portion of matter and was known as the smallest building block of
the universe.
A. Particle
B. Photon
C. Portion
D. Product
2. The theory that states all matter and light shows the characteristics of both
wave and particle.
A. Dual wave-portion theory
B. Wave-dual particle theory
C. Wave-particle duality theory
D. Duality of wave-product theory
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3. A point particle with a negative electric charge.
A. Atom
B. Electron
C. Neutron
D. Proton
4. A disturbance that travels through a space-time.
A. Diffraction
B. Photon
C. Reflection
D. Wave
5. He was the first to coin the term “electron” for the electric charge quantity.
A. Albert Einstein
B. Christiaan Huygens
C. Joseph John Thomson
D. George Johnstone Stoney
6. He discovered electron particles using cathode ray tube.
A. Isaac Newton
B. Francesco Grimaldi
C. Joseph John Thomson
D. George Johnstone Stoney
7. He proposed the particle theory of light.
A. Isaac Newton
B. Louis de Broglie
C. Max Planck
D. Thomas Young
8. He proposed the wave theory of light.
A. Max Planck
B. Isaac Newton
C. Thomas Young
D. Christiaan Huygens
9. He used the double slit experiment to observe the behavior of electrons.
A. Albert Einstein
B. Max Planck
C. Louis de Broglie
D. Thomas Young
10. He hypothesized that the wave-like behavior of electrons seen in light can
also be present in matter.
A. Isaac Newton
B. Louis de Broglie
C. Thomas Young
D. Christian Huygens
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TRUE OF FALSE
Directions: Write the word TRUE if the statement is correct and FALSE if
otherwise.
____________ 11. Electrons have no known mass and slightly bigger than proton.
____________ 12. Wave interference can be applied to sound and light.
____________ 13. When the crest part of a wave meets another crest, sound will be
produced.
____________ 14. When there is no wave interference, no sound and light is
produced.
____________ 15. The dual nature of electrons paved the way for quantum physics.
Lesson
1
Is an Electron a Particle or a
Wave?
We all know that atom is the building block of all matter in the universe. These
extremely small particles are made up of a few even smaller particles. The earliest
particles discovered that make up an atom are protons, neutrons and electrons. But
scientists did not stop looking for the fundamental particles of matter and what
“holds” them together. Recent discoveries suggest that quarks, which make up
protons and neutrons, are another type of fundamental particle. Together with the
leptons, quarks make up the stuff we think of as matter.
Large parts of modern physics and chemistry are based on the study of energy levels
of various atomic and molecular systems. Through the advancement in technology,
laboratory instruments are now able to contain and observe individual electrons
while telescopes can detect electron plasma by its energy emission. All these were
the result of understanding the atomic and molecular behavior of the subatomic
particles, specifically the electrons.
This lesson will help enhance your understanding about the molecular behavior of
electrons and how its discovery led to the development of the wave-particle duality
theory.
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What’s In
CROSSWORD PUZZLE
ACROSS
3. Electromagnetic wave visible to the naked eye
4. Positively charged particle
5. Quantized particles
DOWN
1. Negatively charged particle
2. Building block of matter
Notes to the Teacher
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What’s New
Tell something about the illustrations. Relate your answers on science concepts.
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What is It
Is Electron a Particle or a Wave?
This question may seem a simple one but, in the scientists’, inquisitive minds, this
is not so. In science, a particle is described as a minute portion of matter and is also
referred to as the smallest known building blocks of the universe. This means that
everything that makes up matter and universe is called particle. So how can electrons
become a wave? Well, the first thing that we need to understand is to discover more
about electrons. Are you ready? If yes, then let us proceed.
The electron is a subatomic particle that has a negative electric charge. It has a no
known structure and is believed to be a point particle. It has a mass that is
approximately 1836 times less than that of the proton. The anti-particle of the
electron is called the positron which is identical to electron except that it is producing
a pair (or more) of gamma ray photons. The name “electron” was introduced for the
electric charge quantity in 1894 by Irish physicist George Johnstone Stoney. The
electron was identified as a particle by Joseph John Thomson in 1897 using the
cathode ray tubes that enabled him to calculate the charge to mass ratio. He won a
Nobel prize for his work.
Then, where does the idea of electron being a wave come from? It is like having two
different worlds mold into one! A sound impossible, isn’t it? Let us continue exploring
by understanding what a wave is and if electrons manifest this wave-like behavior.
In physics, a wave is described as a disturbance that travels through space-time and
medium accompanied by transferring energy from one place to another. A medium
may be a substance or material that carries the wave. The wave medium is not the
wave and it does not make the wave; it merely transports the wave from its source to
other locations. Remember, waves transfer energy and not matter. Thus, waves are
said to be an energy transport phenomenon.
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Consider a slinky wave as an example.
Evidently, in describing these two words, waves and particles are very different. We
can say that a particle is a small thing, finite object. You can hold a particle in your
hand. Particles have momentum and positions. On the other hand, waves are
oscillations, they are not localized. When the waves meet, crest meets crests, it is
called constructive interference. When the waves cancel each other, no interaction at
all, it is called destructive interference.
Photo Credit: http://www.reachoutmichigan.org/funexperiments/agesubject
/lessons/ bubbles.html
We can apply this wave interference in sound and light. When two waves meet,
sounds are produced, light is present. When there is no wave interaction, no sounds
are created and only darkness.
Now, how is electron become a particle and exhibit wave-like behavior at the same
time? Let us go back to memory lane by tracing how it all started.
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Lesson
2
Evidence of Wave-like
Behavior of Electrons
Two famous scientists in the 1600s, Christian Huygens and Isaac Newton were both
working on the theories for the behavior of light. Huygens proposed a wave theory of
light while Newton’s was a “corpuscular” (particle) theory of light. Newton believed
that light was made up of small particles and these particles would naturally have
mass too. Since light particles have mass, he deduced that a beam of light parallel
to the surface of the earth would bend downward due to the pull of earth’s gravity.
On the other hand, Huygens believed that light was made up of vibrating waves
perpendicular to the direction of the light travels. With this concept, he was able to
formulate a way to visualize wave propagation. Huygen suggested that light wave
peaks form surfaces like the layers of an onion. In a vacuum or other uniform
mediums, the light waves are spherical and these wave surfaces advance or spread
out as they travel at the speed of light. This Huygen’s Principle explains why light
shining through a pin hole or slit will spread out rather than going in a straight line.
In 1803, Thomas Young studied the interference of light waves using the double-slit
experiment. By shining light through a screen with two slits equally separated, the
light emerging form the two slits, spread out according to Huygen’s principle.
Eventually the two wave fronts will overlap with each other. His experiment firmly
supported Huygen’s wave theory of light. Later in 1815, August Fresnel supported
Young’s experiments with mathematical calculations.
In the early nineteenth century, diffraction (slight bending) of light had been observed
which firmly support the wave theory of light over Newton’s particle theory. The term
diffraction was first discovered and coined by Francesco Grimaldi, an Italian natural
philosopher. In 1900 Max Planck proposed the existence of a light quantum, a finite
packet of energy which depends on the frequency and velocity of the radiation. The
birth of quantum physics is attributed to Max Planck’s experiment on black body
radiation.
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In 1905 Albert Einstein had proposed a solution to the problem of observations made
on the behavior of light having characteristics of both wave and particle theory. Using
the works of Planck on emission of light to form hot bodies, Einstein suggested that
light is composed of tiny particles called photons and each photon has energy. This
finding came to be known as the photon theory of light which later led to the
conceptualization of quantum mechanics in the twentieth century.
After the wave-particle dual behavior of electron in light was accepted, another
scientist took a leap by testing the hypothesis in matter. Louis de Broglie made a
bold assumption and performed experiments to confirm whether the same
observation can be seen in matter. In 1924, he was able to observed wave properties
of the particle when beams of electrons and neutrons were directed at crystals and
diffraction patterns were seen. He concluded that everything has a wavelength but
the wave properties of matter are only observable for very small objects. He showed
that the wave-particle duality was not merely on light but can be exhibited by both
radiation and matter. Thus, the wave-particle duality theory which states that matter
and light exhibit the behaviors of both waves and particles depending upon the
circumstances or condition was accepted.
Further studies were made by De Broglie and he found out that the probability of
finding a particle at a particular location is related to the wave associated with the
particle. The larger the amplitude of the wave at a particular point, the larger the
probability that the electron will be found there. Similarly, the smaller amplitude the
smaller the probability. This means that the larger the objects, the smaller
wavelengths can be observed. But for small objects, wavelengths are more distinct
as shown in the double slit experiment with electrons. Because of his profound
discovery, de Broglie won a Nobel Prize.
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What’s More
Activity 1.1 Experimental Evidence of Electrons Behaving
like a Wave
Atoms are the building blocks of matter. This means that everything around us is
made up of atoms, both for the living and non-living things.
The following video links will help you enhance your understanding about the waveparticle dual nature behavior of electrons. Watch and analyze before answering the
“Activity Assessment.”
Part A. Nature of light:
https://www.youtube.com/watch?v=J1yIApZtLos
Part B. Wave-Particle Duality: https://www.youtube.com/watch?v=qCmtegdqOOA
Activity 1.2 Guide Questions
Directions: Answer briefly and concisely the following questions.
PART A:
Nature of light
1. How did Newton view about the nature of light?
___________________________________________________________________________
___________________________________________________________________________
2. What particular evidence shows that light is a particle?
___________________________________________________________________________
___________________________________________________________________________
3. What particular evidence shows that light is a wave?
______________________________________________________________________________
______________________________________________________________________________
4-5. Is light a particle or a wave?
______________________________________________________________________________
______________________________________________________________________________
PART B: Wave Particle Duality
6-8.
Describe how the following behave as they enter the two slits:
A. Particle ___________________________________________________________________
______________________________________________________________________________
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B. Wave _____________________________________________________________________
______________________________________________________________________________
C. Quantum objects _________________________________________________________
______________________________________________________________________________
9. What do you think will happen if an observer modifies the experiment?
______________________________________________________________________________
______________________________________________________________________________
10. Briefly explain the Wave-Particle Duality theory.
______________________________________________________________________________
______________________________________________________________________________
What I Have Learned
Directions: Briefly describe the illustrations by citing scientific explanation based on
the wave particle duality theory.
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
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__________________________________________________________________________________
__________________________________________________________________________________
What I Can Do
Using the suggested materials, try to perform this experiment at home for you to
have an actual observation on how electrons behave as a particle and a wave.
Needed Materials:
• Laser (be careful not to shine this in anyone’s eyes)
•
Needle
•
Tape
•
Table
•
White printer paper
•
Dark room
•
Flat wall
Procedure:
1. Fold and unfold your sheet of printer paper once so that it can stand upright.
2. Make a tiny hole in your paper with your needle.
3. Stand your printer paper upright on a table that is at least ten feet away from the
wall.
4. Use your tape to mount your laser pointer to a stable object, like a heavy book.
Place the mounted laser on the table.
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5. Turn your laser on. Adjust the angle of your laser so that it passes through the
hole in your paper and onto the wall. What did you see? Is it what you expected
to see?
6. Make another hole in your paper right next to the first one so that they’re as close
together as possible without creating one larger hole.
7. Adjust your laser so that it now passes through both holes. Observe the shapes
created on the wall. What do you see? Was it what you expected to see?
8. Cover one of the holes with a small piece of paper, leaving the other open. How
does the projected image on the wall change?
Guide Questions:
1. Describe the pattern of light as it passes through:
A. One slit _________________________________________________________________
B. Two slits _________________________________________________________________
2. How does the projected image on the wall change when one of the holes was
covered?
______________________________________________________________________________
______________________________________________________________________________
3. What can you infer from the activity about the behavior of light particles?
______________________________________________________________________________
______________________________________________________________________________
Assessment
MULTIPLE CHOICE
Directions: Choose the LETTER of the correct answer.
1. Light demonstrates the characteristics of______.
A. Particle
C. Both wave and particle
B. Wave
D. Neither particle nor wave
2. Wave particle duality best applies in analyzing the motion of ________.
A. Projectile
C. Heavenly bodies
B. Space shuttle
D. Electrons
3. Which phenomenon best supports the theory that matter has a wave nature?
A. Electron momentum
C. Photon momentum
B. Electron diffraction
D. Photon diffraction
4. On the atomic level energy and matter exhibit the characteristics of _______.
A. Particles only
C. Neither particles nor waves
B. Waves only
D. Both particles and waves
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5. What does the theory of modern Physics tells us about light?
A. Demonstrate wave property only
B. It combines wave and particle properties
C. Exclusively shows particle property
D. It has neither wave nor particle properties
6. Which of the following is an example of light behaving like a particle?
A. Photoelectric effect
C. Interference
B. Doppler effect
D. Diffraction
7. What was the first experiment to show that light is a wave?
A. The oil drop experiment
B. The gold foil experiment
C. The double-slit experiment
D. The propagation of wave experiment
8. Why is laser light is used in double-slit experiment?
A. It is made up of different wavelengths.
B. It is made up of coordinated waves of exactly the same wavelengths.
C. It is made up of uncoordinated beam of light.
D. It is made up of intense beam of light.
9. What wave -like property of light is shown when light bends as enters an
opening?
A. Reflection
C. Refraction
B. Diffraction
D. Interference
10. What does the dark fringe patterns of light wave on the screen in double slit
experiment show?
A. Destructive interference
C. Constructive interference
B. Reflected interference
D. Diffracted interference
MATCHING TYPE:
Directions: Match the scientist in Column A with their contribution in Column B.
Write the LETTER of the answer on the space provided.
COLUMN A
______ 11. Christiaan Huygens
COLUMN B
A. Proposed the particle theory of light
______ 12. Isaac Newton
B. Proposed light as electromagnetic wave
______ 13. Louis De Broglie
C. Proved the dual nature of electron in light,
radiation, and all matter
______ 14. Max Planck
D. Performed the double-slit experiment
______ 15. Thomas Young
E. Originator of quantum physics
F. Proposed the wave theory of light
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Additional Activities
Research Work
Directions: Research at least one invention made from the discovery of the waveparticle duality of electrons. Choice of presentation can be through PowerPoint or
Microsoft word/WPS application.
Rubric for Grading
The research work will be scored from 1 to 5, with 5 being the highest in every
criterion. The criteria for grading are as follows:
Criteria
Organization and Content
Picture
Cited Resources
Timeliness
Expectations
Organization of idea and content is accurate.
Language used is in own words, not copy pasted
from the source.
Clear and authentic. Image should bear the credit
source below the picture.
Follows the Chicago Manual style in citing
references.
Should be submitted on time. Deduction of one
point per day will be administered.
WORD SEARCH ACTIVITY
Directions: Find and encircle the missing words hidden in the grid. The words may
be hidden in any direction.
Wave
Particle
Interference
Electron
Medium
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