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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) Teacher’s Language No. Activities Exploration 1. OK. Look at the slide. We begin from Dalton Teacher explains about the atomic theory to modern atomic theory. discovery and development of atomic structure, 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 Come back to the matter. The one atomic the atomic structure. 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) No. Activities Teacher’s Language 1. That’s all the time we have for today. Please, Propose the next topic 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 Yogyakarta, ……… 2012 Prinsiple Subject Teacher Reskunanda Adhi W Evaluation The Discovery and Development of Atomic Structure Event Result Excess Weakness Person Experiment involved Democritus … … … … Dalton … … … … JJ Thompson … … … … Rutherford … … … … Niels Bohr … … … … … … 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 number of neutrons : 12 c. number of protons: 47 number of electrons :47 number of neutrons : 61 d. number of protons: 55 number of electrons :55 number of neutrons : 78 e. number of protons: 83 number of electrons :83 number of neutrons : 126 2. Classify the following atoms into isotope, isobar and isoton. Isotope : and and Isobar : and Isoton : , , and Psycomotoric Perception sheet of students No Name Assessment scale: 1 : Very less 2 : Less 3 : Enough 4 : Good 5 : Very good Participation Having a notion Asking Correct reactions Average