1. SLM-GR-9-Q2-M-1A-Electronic-Structure-of-Matter (2)

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Science 9

Quarter 2 – Module 1A:
Electronic Structure of Matter

Self-Learning Module

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Science - Grade 9 Electronic Structure of Matter
Self-Learning Module
Quarter 2 Module 1A
First Edition, 2020

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authors do not represent nor claim ownership over them.

Published by the Department of Education
Schools Division Superintendent: Gladys Amylaine D. Sales CESO VI
Assistant Schools Division Superintendent: Michell L. Acoyong CESO VI

Development Team of the Self Learning Module

Writer: Kevin Clyde A. Ong
Editors: Ma. Trina Jeraldine M. Ambait, Osward P. Acebedo
Pamela Grace E. Justiniani, Osward P. Acebedo,
Reviewers: Edna Rose P. Gueco
Kevin Clyde A. Ong
Illustrators: Kevin Clyde A. Ong
Layout Artists: Gladys Amylaine D. Sales
Management Team: Michell L. Acoyong
Janalyn B. Navarro
Edna Rose P. Gueco
Ellen G. Dela Cruz

Printed in the Philippines by

Department of Education Region VI Division of Bacolod City

Office Address: Rosario-San Juan Sts., Bacolod City 6100
Telefax: (034) 704-2585
E-mail Address: [email protected]

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Introductory Message

For the facilitator:
This Self-Learning Module (SLM) is a stand-alone resource material in

Science which is intended for the learners of the Division of Bacolod City. Learners
who do not have online accessibility or who do not want to risk face-to-face learning
may utilize this module. This includes a learner-friendly pretest, self-check exercises,
and other modes of instructions for learners and teachers who are geographically
remote from each other. This covers topics in Grade 9 in the 2nd Quarter with
corresponding activities for learners to achieve the most essential learning
competencies and lesson objectives.

Each exercise in this module is designed for independent learning and
ac ce. H e e , e e ha he ea e a e , e de b g , g a d a
relatives at home will guide and support them as they accomplish the given tasks.
Furthermore, explain to students that taking the tests diligently will allow them to
learn their lessons for their academic progress. Most importantly, remind them to
answer the given activities on a separate answer sheet and handle this module with
utmost care.

For the learner:

This Self-Learning Module (SLM) is a learner-friendly resource material in
Science which is specifically designed for your learning needs and progress. Your
patience and dedication in reading and answering the exercises will help you
successfully achieve the objectives. You are free to ask assistance from your
teachers, parents, siblings, friends, and family members whom you think can help
you best. Read each lesson carefully and follow the instructions for your activities.

Remember to answer the given exercises in a separate sheet of paper. When
you are done, kindly submit it to your teacher who will check and evaluate your level
of competency.

You can do it! Good luck and God bless.

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Parts of the Self-Learning Module
The following are the parts of this module that will help you finish your tasks.

Read the following descriptions below to better understand each part.

I Need to Know This part will be your guide to learn in the
specific lessons specifically your skills and
competencies.

I Will Check on This This contains a 10-item pre-test that will
check what you already know.

Lesson Overview This section will give you the topic,
information and concepts as a brief
I Will Do This discussion for you to learn.

I Learned This It is in this part that the new lesson will be
I Practice This introduced to you in different ways: a story, a
I Apply This poem, a problem opener, an activity, or a
I Test Myself situation. You will be given specific
References instructions on how to go about the activity.

In this part helps you generalize your
understanding of the concepts. This includes
a short fill-in the blanks summary of the topic.

This provides you questions and exercises to
help you deepen your understanding of the
concept.

This section includes an activity or exercises
that will help you apply your knowledge into
real-life situations

This is composed of 10-item exercises to
assess if you have attained the learning
competency.

This is a list of all sources used in developing
this module

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I Need to Know

This module was designed and written with you in mind. It is here to help you
de cribe ho he Bohr model of he a om impro ed R herford a omic model
S9MT-IIa-21. The scope of this module allows you to use it 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.

This module is composed of one lesson only:
Lesson 1 R he f d a d B h M de f a A

After going through this module, you are expected to
1. d ffe e a e B h a c de f R he f d a c de ,
2. c e ef e e ade b B h A c M de f R he f d , a d
3. draw a line representation on how alpha particles have passed through,
have deflected, and have redirected back towards the source.

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I Will Check on This

Read each sentence carefully. Select the letter of the best answer.

1. Which of these items below was NOT discovered using cathode ray tube?

A. electrons C. protons

B. neutrons D. x-rays

2. Which of the following statements describes the neutron?
A. It is negatively charged.
B. It is part of alpha-radiation.
C. It is discovered by Goldstein.
D. It is the lightest subatomic particle.

3. Which of the following phenomena caught Rutherford into surprise in his
experiment?

A. Most of the alpha particles were not deflected.
B. Some alpha particles did not pass through the foil.
C. Some alpha particles redirected back toward the source.
D. All of the above

4. Which subatomic particle/s account/s for the mass of the atom?

A. electron and neutron C. neutron and proton

B. electron and proton D. neutron only

5. Who is regarded as the father of modern atomic theory?

A. Dalton C. Rutherford

B. Lavoisier D. Thomson

6. To which of the following options below does mass of an atom is concentrated?

A. electron C. nucleus

B. neutron D. proton

7. Which of the following objects below was used by Rutherford in leading to his

discovery of the nucleus of an atom?

A. alpha particle C. gold foil

B. aluminum foil D. silver foil

In items 8-10, choose among the following choices:

A. Nuclear model C. Raisin bread model

B. Planetary model D. Solid sphere model

8. Which of the following atomic models was discovered by Ernest Rutherford?

9. Which of the following atomic models was discovered by Neils Bohr?

10. Which of the following atomic models was discovered by J.J. Thomson?

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1Lesson Rutherford and Bohr’s
Model of an Atom

Lesson Overview

In Grade 8, you have learned how atomic structure develops over time as to
how scientists discover new ideas through experiments. It started with the
philosophers, Leucippus and Democritus until such, John Dalton formulated his
atomic theory and later on regarded as the Father of Modern Atomic Theory. You
have also learned that atom is mostly made up of empty space and its mass is
concentrated in the nucleus, where you find the protons and the neutrons. This
model was explained by Rutherford. It has worked well during his time. However, it
was only able to explain a few simple properties of atoms and could not explain why
metals or compounds of metals give off characteristic colors when heated in a flame.
These unresolved ideas paved way for a development of a new model to describe
the behavior of atoms.

N e B h ef ed R he f d de f a a . Ba ed h e e e ,

Bohr described the electron to be moving in definite orbits around the nucleus. Much

later, scientists discovered that it is impossible to determine the exact location of

e ec a a . I Ac 1, d ffe e a e B h a c de f

R he f d a c de . Le h.

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I Will Do This

Ac i i 1: R he fo d Model e Boh Model

S d he a f R he f d a d B h de f a a a d ead he

selection below.

LEGEND:

Nucleus

Electron

R he f d M de B h M de

Figure 1. Rutherford and Bohr Atomic Model

As we look at our surroundings, it looks pretty solid. We hit a wall with our
body, and we stop. We think of matter as occupying space. But there is a lot of
empty space in matter. In fact, most of the matter is empty space.

The Gold Foil Experiment and the Nuclear Model
In 1911, Ernest Rutherford, along with his co-workers, Has Geiger and Ernest

Marsden started a series of experiments that would contribute to the development of
an atom. They bombarded very thin sheets of gold foil with a type of natural, a
positively charged radioactive particle with a mass about four times that of a
hydrogen atom called the alpha particles. In their experiment, the scientists are
expecting that all alpha particles would pass through the gold foil with only a very
minor deflection or even none at all. Surprisingly, while most alpha particles were not
deflected, they were few that bounced off at very large angles. Some were redirected
back toward the source.

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Figure 2. R he f d f d g he a e ce age f a ha a c e ha e e def ec ed

Rutherford concluded that all the positive charges and the majority of the

mass of the atom must be concentrated in a very sma ace he a e,

which he called the nucleus. The nucleus is the tiny, dense, central core of the atom

ad c ed f ad e . R he f d a c de beca e

known as the nuclear model.

The Planetary Model
In 1913, a student of Rutherford, Neils Bohr, developed a new model of the

atom. He proposed that electrons are arranged in concentric circular orbits around
the nucleus. Concentric describes something, like circles, that have a common
center. This model is patterned on the solar system and is known as the planetary
model.

Materials: Activity sheet

Procedure
1. Identify similarities and differences between the two pictures.
2. Write your answer on the Answer Sheet attached to this module.

Analysis Questions:

1. Wha a e he d ffe e ce be ee R he f d a d B h A c M de ?
_________________________________________________________________
_________________________________________________________________

2. What are the similarities between R he f d a d B h A c M de ?
_________________________________________________________________
_________________________________________________________________

3. H d d B h de f a a ef ed R he f d de f a a ?

_________________________________________________________________

_________________________________________________________________

_________________________________________________________________

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I Learned This

Fill in the blanks. Select your answer from the box.

nucleus gold foil solar system

nuclear model planetary model

I have learned that in 1911, Ernest Rutherford, along with his co-workers, Has

Geiger and Ernest Marsden started a series of experiments that would contribute to

the development of an atom. They have use very thin sheets of 1.______________

with a type of natural, positively charged radioactive particle with a mass about four

times that of a hydrogen atom called the alpha particles. Also, there is this central

core of the atom and is composed of protons and neutrons known as

2._______________. W h h , R he f d a c de beca e as the

3.__________________.

In 1913, a student of Rutherford, Neils Bohr developed a new model of the
atom. He proposed that electrons are arranged in concentric circular orbits around
the nucleus. This model looks like a 4._______________ and is known as the
5._____________________.

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I Practice This

Materials: Activity sheet, 3 crayons (black, blue, and red)
Each horizontal line that you draw will represent an alpha particle. Using the

answer sheet attached to your module, draw a 5 horizontal lines that pass through
an atom using your black crayon, 2 horizontal lines that are partially deflected using
your blue crayon, and 2 horizontal lines that were redirected back toward the
source using your red crayon. You may also use your ball pen with black, blue, and
red inks in case you do not have crayons.

S

O

U

R

C

E

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I Apply This

The images on Column A are atomic models of atoms as explained by
Rutherford. On Column B, draw the atomic model as refined and explained by Bohr.
Consider the first item as an example.
TAKE NOTE: There could only be a maximum of 2 electrons found on the first
energy level.

Column A Boh Column B
R he fo d Model of an A om Model of an A om
1.

2.
3.

4.

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I Test Myself

Multiple Choice. Read each item carefully. Select the letter of the best answer.

1. On which year did Ernest Rutherford, along with his co-workers, Has Geiger and

Ernest Marsden start a series of experiments that would contribute to the

development of an atom?

A. 1911 C. 1915

B. 1913 D. 1917

2. Which of the following objects did Rutherford and the team use the discovery of

the nucleus of an atom?

A. alpha particle C. gold foil

B. aluminum foil D. silver foil

3. Which of the following statements describes alpha particle?
A. natural, negatively charged radioactive particle with a mass about two times of
a hydrogen atom
B. natural, neutral charged radioactive particle with a mass about four times of a
hydrogen atom
C. natural, positively charged radioactive particle with a mass about four times of a
hydrogen atom
D. none of the above

4. In later years after the discovery of atomic model of Rutherford, his student, Neils
Bohr also refined and discovered another atomic model. How did he describe and
propose the arrangement of electrons in his model?

A. arranged in linear order moving towards the nucleus
B. arranged in linear order moving away from the nucleus
C. arranged in concentric circular orbits around the nucleus
D. arranged in circular-spiral orbit moving away to the nucleus

5. T h ch f he f g e de Bh de a e ed ?

A. digestive system C. metric system

B. international system D. solar system

References

Sc e ce 9 Lea e Ma e a . 100-104

EASE M d e Che M10: Wha I de he A

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Key Answer

Module 1A Electronic Structure of Matter
Le on I R he fo d and Boh Model of an A om

I Will Check on This I Will Do This
1. B 1. In R he fo d a omic model elec on e ol e a o nd he n cle in
2. B
3. A an orbit but it is not really specified how they are arranged while in
4. C Boh a omic model elec on a el in a ecific o bi .
5. A 2. (1)The protons are centered in the nucleus. (2) Electrons occupy a large
6. C space of the atom outside the nucleus.
7. C Boh model efined R he fo d model b o o ing ha elec on
8. A travel in orbits that have specific energy levels.
9. B
10. C I Practice This

I Learned This
1. gold foil
2. nucleus
3. nuclear model
4. solar system
5. planetary model

I Test Myself I Apply This
1. A 2.
2. C 4.
3. C
4. C 14
5. D

1.

3.

PostTest

Multiple Choice. Read each item carefully. Select the letter of the best answer.

1. All these were discovered because of the cathode ray tube, EXCEPT:

A. x-rays C. protons

B. electrons D. neutrons

2. Which of the following statements describes the neutron?
A. It is positively charged.
B. It is part of alpha radiation.
C. It is about the same mass as a proton but without an electric charge found in

the nucleus
D. It is the lightest subatomic particle.

3. Wh ch f he f g he e a d d cc R he f d e e e?

A. All of the alpha particles were not deflected

B. Some alpha particles went back to the source.

C. Some alpha particles did not pass through the foil.

D. All of the above

4. Which subatomic particle/s can be found at the central core of an atom?

A. electron and proton C. electron and neutron

B. neutron and proton D. neutron only

5. He is one of the first atomist who believed that all things are made up of atoms?

A. Dalton C. Bohr

B. Democritus D. Rutherford

6. To which of the following locations does mass of an atom is concentrated?

A. center C. anywhere in the atom

B. outermost part D. cannot be determined

7. Which of the following experiments did Rutherford conduct in discovering the nucleus of

an atom?

A. aluminum foil experiment C. gold foil experiment

B. gamma particle experiment D. silver foil experiment

In items 8-10, choose among the following choices:

A. John Dalton C. Ernest Rutherford

B. J.J. Thomson D. Neils Bohr

8. Who among the scientists is regarded as the father of modern atomic theory?
9. Who among the scientists is known for his discovery of planetary model?
10. Who among the scientists is known for his discovery of nuclear model?

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For inquiries or feedback, please write or call:

Department of Education Division of Bacolod City

Office Address: Rosario-San Juan Sts., Bacolod City, Philippines 1600

Telefax: (034) 704-2585

e-mail Address: [email protected]

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Key Answer to Post Test

FOR TEACHER S USE ONLY. Do no a ach hi po ion o he SLM fo den

1. D 6. A
2. C 7. C
3. A 8. A
4. B 9. D
5. B 10. C

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Science 9
Quarter 2 – Module 1A:
Electronic Structure of Matter

ANSWER SHEET

I Will Check On This (Capital letters only)

1. 6.
2. 7.
3. 8.
4. 9.
5. 10.

I Will Do This

Analysis Questions:
1. What are the d ffe e ce be ee R he f d a d B h A c M de ?
________________________________________________________________
________________________________________________________________

2. Wha a e he a e be ee R he f d a d B h A c Model?
________________________________________________________________
________________________________________________________________

3. H d d B h de f a a ef ed R he f d de f a a ?

________________________________________________________________

________________________________________________________________

________________________________________________________________

I Learned This
1.
2.
3.
4.
5.

I Test Myself
1.
2.
3.
4.
5.

Plea e efe o a ached hee fo I P ac ice Thi and I Appl Thi

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I Practice This
Materials

Activity sheet, 3 crayons (black, blue, and red)
Each horizontal line that you draw will represent an alpha particle. Using the

answer sheet attached to your module, draw a 5 horizontal lines that pass through
an atom using your black crayon, 2 horizontal lines that are partially deflected using
your blue crayon, and 2 horizontal lines that were redirected back toward the
source using your red crayon. You may also use your ball pen with black, blue, and
red inks in case you do not have crayons.

S
O
U
R
C
E

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I Apply This

The images on Column A are atomic models of atoms as explained by

Rutherford. On Column B, draw the atomic model as refined and explained by Bohr.

Consider the first item as an example.

TAKE NOTE: There could only be a maximum of 2 electrons found on the first

energy level.

Column A Column B

R he fo d Model of an A om Boh Model of an A om

1.

2.

3.

4.
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