pengembanganmediakimia.files.wordpress.com€¦ · Web viewUnderstanding atomic structure, the periodical properties of elements, and chemical bonding. Basic Competency : Understanding

LESSON PLAN

School : State Senior High School ………………

The Lesson : Chemistry

Subject : Atomic Structure

Grade/ semester : X/ 1

Time Allocation : 2×45 minutes

Standard of Competence :

Understanding atomic structure, the periodical properties of elements, and chemical

bonding.

Basic Competency :

Understanding the structure based Bohr’s atomic model, element’s properties, relative

atomic masses, and the periodical properties of elements, also realizing its regularity by

understanding the electron configuration.

Teaching Objectives :

Students are able to explain the discovery and development of atomic structure,

from Dalton atomic theory to modern atomic theory.

Students are able to determine the atomic structure based of atomic number and the

number atomic masses.

Students are able to categorize the element into isotope, isobar, and isoton based of

atomic number and the number atomic masses.

Indicator :

Students are able to explain the development of atomic theory and model from

Dalton atomic theory to modern atomic theory.

Students are able to explain the atomic structure based of discovery that construct

the development of atomic theory and model from Dalton atomic theory to modern

atomic theory.

Students are able to explain the atomic structure based of discovery that construct

the development of atomic theory and model from Dalton atomic theory to modern

atomic theory.

Students are able to determine the basic particles (protons, electrons and neutrons)

Students are able to determine the atomic structure based of atomic number and the

number atomic masses.

Students are able to categorize the element into isotope, isobar, and isoton based of

atomic number and the number atomic masses.

Teaching Method :

Lecturing

Giving Worksheet

Question Answer Methode

Media components :

Notebook, LCD, Whiteboard, and Worksheet

Learning materials :

Since the ancient Greek until present, atomic theory and model has been

developing. By this mean, we can discover the structure of atom. The progress is

worked by great scientists, such as Democritus, John Dalton, JJ Thompson, Rutherford,

Chadwick, Millikan, Niels Bohr, Schrodinger, de Broglie, and Heisenberg. From those

we can determine the atomic structure categorize the element into isotope, isobar, and

isoton based of atomic number and the number atomic masses.

Dalton atomic theory and model

Dalton proposed the first modern atomic theory that all matter is made of tiny

particles called atoms. According to Dalton’s atomic theory, atoms are solid particles

which are indivisible. So, based on Dalton’s atomic theory, atom can be drawn as

If there is atom X combine with atom Y, it’s product XY molecule. According to

Dalton’s atomic theory, the scheme of reaction is

+

X + Y XY

So, the conclusion is atom can be combined in definite, fixed proportions to make

compounds.

JJ Thompson atomic theory and model

In Thompson’s experiment, he was using a glass tube called cathode ray tube. The

figure of cathode ray tube can illustrated bellow:

Figure 1. Cathode Ray Tube

1. The experiment by JJ Thompson

Within the experiment, when the tube was connected to a source of electrical

energy and Thompson placed the electric field, the cathode light was attracted by

positive plate, but repelled by negative plate ( look the figure 1.) and when he

placed magnetic field on the beam pathway, Thompson showed that a positive side

of magnet made the cathode ray bend towards and the opposite happened when he

used a negative side of magnet (from the video). That’s mean the cathode ray had to

be made of negatively charged particle that called electron.

2. Thompson’s atomic theory and model

This surprised Thompson, because the atoms of the gas were uncharged. Where

had the negative charged come from?

Thompson conclude that the negative charges came from within the atom). Since

the gas was known to be neutral, having no charge, he reasoned that there must be

positively charged particle in the atom.

So the atomic theory by JJ Thompson is the atom contained negatively charged

particle mixed evenly into a positively charged sphere. The negative and positive

charged cancelled each other out, so that atoms would have no charged if complete.

The figure of Thompson’s atomic model is

Rutherford atomic theory and model

From Rutherford’s experiment, got some data:

Alpha particles are positively charged, struck the sheet of gold foil.

The sheet of gold foil contains gold atoms.

97,99% alpha particles are transmitted. 2% alpha particles are diverted.

0,01% alpha particles are reflected.

Most of alpha particles are transmitted because they encounter the free space in the

gold atoms; therefore, most space of atom is free space. Meanwhile, the alpha particles

diverted are those touching the nucleus which is a big size and the ones reflected are

alpha particles which accurately collide with the nucleus and undergo repulsion force

because the mass atomic nucleus is positively charge.

Conclusion:

a. An atom consists of an atomic nucleus which is positively charged. The nucleus of

atom contains almost entire mass of the atom and is surrounded by electrons

which are negatively charged as in the solar system model.

b. Entirely, an atom is neutral because the number of its positive charges (protons) is

equal to that of its negative charges.

c. During revolving the nucleus, the centripetal force on electrons in an atom is

produced by the force of attraction between the electrons and nucleus (Coulomb

force).

Niels Bohr atomic theory and model

Niels Bohr completed Rutherford theory by placing the quantum theory of Plank

and Einstein in it. According to Bohr, the electron motion around the nucleus must

progress in certain angle momentum.

Every energy level will be filled by certain amount of electron. According to Bohr,

the maximum electron in every level was 2n2.

Letters K, L, M, and so on declared as electron orbital in every level. Level 1 (n = 1)

called orbital K, n = 2 called orbital L, and so on. The electron, which falls from low

energy to upper level, will cause energy absorption and produce discreet color.

The Bohr’s atomic model is:

In brief, the theory mention by Bohr can be comprehended as follow:

1. Electrons are moving around nucleus in discreet level of energy.

2. Electron may transfer from one energy level to another energy level.

a. From low energy to upper level is called excitation, and it

absorbs energy.

b. From high energy to lower level is called de-excitation, and it

release energy.

Proton is positively charged particle which was discovered by Eugene Goldstein

by continuation rays experiment.

J. Chadwick discovered neutron from the shooting of beryllium using alpha

particles and then this neutron known as the particle composing the atom

nucleus.

Neutron is uncharged particles.

Symbol of Atom

X = the name/symbol of atom

A = mass number of atom = number of protons + number of

neutrons

Z = atomic number = number of protons = number of electron

Isotope is one of two or more species of an element that have the same atomic

number, but different mass number.

Isobar is atom which come from different element but they have same mass

number

Isoton is atom which come from different element but they have same number of

neutrons.

Teaching and Learning Objectives

Opening ( 5 minutes)

No. Activities Teacher’s Language

1. Greeting Good morning, class.

2. Asking for student’s condition How are you today?

3. Leading a prayer Before we start our lesson today, let’s pray

together. Prayer, do. … Thank you.

4. Checking attendance Who is absent today?

5. Apperception Have the relation with our lesson today we will

talk about chemistry. You know that almost of

the “things” in our world has the relation with

chemistry (give example). And this things

begin from the smaller particle that construct

this ”things”. Begin from this. “the calk”. What

do you think when we broken into 2 parts?

And when we grind until become the powder

and it can’t grind anymore or we can called it

the matter could not be divided into smaller

and smaller pieces forever. You know what is

it? Yes you right its called atom. And this

theory based of Democritus. Now we will

study about the discovery and development of

atomic structure, from Dalton atomic theory to

modern atomic theory.

Core activities ( 80 minutes)


1.

Exploration

Teacher explains about the

discovery and development of

atomic structure, from Dalton

atomic theory to modern

atomic theory.

OK. Look at the slide. We begin from Dalton

atomic theory to modern atomic theory.

Giving task to student. OK. From my explanation I want you to make

resume about the discovery and development

of atomic structure, from Dalton atomic theory

to modern atomic theory in your book. And

you can follow the format like in the slide. And

the next time I will check your work.

Continue the explanation about

the atomic structure.

Come back to the matter. The one atomic

structure with the other has the different in the

number of proton, electron, and neutron. OK

we will study about it. (study about atomic

number and the number atomic masses and

isotope, isobar, and isoton)

2. Elaboration

Giving the exercise I have the exercise to you. Please do it. I give

you 15 minutes to do it and I want one of you

share your answer to the class.

3. Confirmation

Explaining the right answer Teacher Explains answer the problem of

practice which have been done student

Closing ( 5 minutes)


1. Propose the next topic That’s all the time we have for today. Please,

read the next matter about electron

configuration and relative atomic masses.

Don’t forget the task.

2. Leave Taking See you later.

Learning Source

Justiana, Sandri and Muchtaridi. 2009. Chemistry for Senior High School 1 Year X.

Jakarta: Yudhistira.

Purba, Michael. 2007. Kimia untuk SMA Kelas X Semester 1. Jakarta: Penerbit

Erlangga.

Sunardi. 2007. Kimia Bilingual Untuk SMA/ MA Kelas X Semester 1 dan 2. Jakarta:

Yrama Widya.

Tim Penyusun. 2010. Kreatif Kimia untuk SMA/ MA Kelas X Semester Gasal. Klaten:

Viva Pakarindo.

Assessment :

Cognitive : The result of student Exercise

Psycomotoric (enclosure)

Affective : Attendance

Approved by

Prinsiple

Yogyakarta, ……… 2012

Subject Teacher

Reskunanda Adhi W

Evaluation

The Discovery and Development of Atomic Structure

Event

Result Excess WeaknessPerson

involvedExperiment

Democritus

Dalton

JJ Thompson

Rutherford

Niels Bohr

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Discovery of

Proton

Discovery of

Neutron

…

…

…

…

Exercise

1. Determine the number of protons, electrons and neutrons of the following atoms

a.

b.

c.

d.

e.

2. Classify the following atoms into isotope, isobar and isoton

, , , , ,

Answer

1. the number of protons, electrons and neutrons of the following atoms

a. , number of protons: 6

number of electrons :6

number of neutrons : 6

b. number of protons: 11

number of electrons : 11


c. number of protons: 47



d. number of protons: 55



e. number of protons: 83



2. Classify the following atoms into isotope, isobar and isoton.

Isotope : and

and

Isobar : and

Isoton : , , and

Psycomotoric

Perception sheet of students

No Name ParticipationHaving a

notionAsking

Correct

reactionsAverage

Assessment scale:

1 : Very less

2 : Less

3 : Enough

4 : Good

5 : Very good

Documents

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