This document is a teacher instruction manual for chemistry and physics for Grade 10 in Sri Lanka. It contains 3 main sections: a detailed syllabus, an activity continuum to implement the syllabus, and instruments for assessment. The detailed syllabus outlines competency levels and content for each subject, as well as guidance for school policies. The activity continuum provides sample classroom activities aligned to competencies. The final section gives guidance on assessment to evaluate student learning. The overall goal is to help teachers implement a new, competency-based curriculum centered around student-focused, active learning.
Effects Of Using Gagne’s Learning Hierarchy On Chemistry Students’ Academic A...IOSR Journals
This study investigates the Effects of Using Gagne’s Learning Hierarchy on Chemistry Students’ Academic Achievement and Anxiety level in Balancing Chemical Equations in Secondary Schools. The study sample used 100 SSII students randomly selected from two Senior Secondary Schools in Katsina Metropolis. The two schools were randomly placed as experimental and control groups each with 50 students. A quasi-experimental pretest-posttest research design was used for the study. The study subjects in the experimental group were taught using Gagne’s learning hierarchy, while the control group was taught using lecture method for the period of six weeks. Two instruments; Balancing Chemical Equation Achievement Test (BCEAT), and Students’ Anxiety Scale Questionnaire (SASQ) with reliability coefficient of 0.79 and 0.78 respectively, were used to collect data for the study. Performances of the two groups were compared using their posttest mean scores. The major findings from the study are: Students taught using Gagne’s learning hierarchy recorded high academic achievement than those taught using to lecture method. The anxiety level of students taught using Gagne’s learning hierarchy tended to be low when compared with students taught using lecture method. Based on the findings, the following recommendations were made: Chemistry teachers should as much as possible arranges concepts taught in Chemistry hierarchically so that students can learn the simple concepts which will help their understanding of abstract or complex concepts.
Effects Of Using Gagne’s Learning Hierarchy On Chemistry Students’ Academic A...IOSR Journals
This study investigates the Effects of Using Gagne’s Learning Hierarchy on Chemistry Students’ Academic Achievement and Anxiety level in Balancing Chemical Equations in Secondary Schools. The study sample used 100 SSII students randomly selected from two Senior Secondary Schools in Katsina Metropolis. The two schools were randomly placed as experimental and control groups each with 50 students. A quasi-experimental pretest-posttest research design was used for the study. The study subjects in the experimental group were taught using Gagne’s learning hierarchy, while the control group was taught using lecture method for the period of six weeks. Two instruments; Balancing Chemical Equation Achievement Test (BCEAT), and Students’ Anxiety Scale Questionnaire (SASQ) with reliability coefficient of 0.79 and 0.78 respectively, were used to collect data for the study. Performances of the two groups were compared using their posttest mean scores. The major findings from the study are: Students taught using Gagne’s learning hierarchy recorded high academic achievement than those taught using to lecture method. The anxiety level of students taught using Gagne’s learning hierarchy tended to be low when compared with students taught using lecture method. Based on the findings, the following recommendations were made: Chemistry teachers should as much as possible arranges concepts taught in Chemistry hierarchically so that students can learn the simple concepts which will help their understanding of abstract or complex concepts.
Classification of the Subject Content of BSE Physical Sciences Majors (2015 C...elio dominglos
Undergraduate research about the Course content of Bachelor of Secondary Education - Physical Sciences majors. this covers how much units and what are the courses taken by the physics majors at Benguet State University, year 2015. Since the curriculum was already changed this serves as reference for those who are making there researches specially the secondary education in BSU.
Yager, robert the development of science teacher programs focus v8 n1 2014William Kritsonis
NATIONAL FORUM JOURNALS (Founded 1982 (www.nationalforum.com) is a group of national and international refereed journals. NFJ publishes articles on colleges, universities and schools; management, business and administration; academic scholarship, multicultural issues; schooling; special education; teaching and learning; counseling and addiction; alcohol and drugs; crime and criminology; disparities in health; risk behaviors; international issues; education; organizational theory and behavior; educational leadership and supervision; action and applied research; teacher education; race, gender, society; public school law; philosophy and history; psychology, sociology, and much more. Dr. William Allan Kritsonis, Editor-in-Chief.
Yager, stuart exemplary science teacher education program nftej v 24 n3 2014William Kritsonis
Dr. William Allan Kritsonis, Editor-in-Chief, NATIONAL FORUM JOURNALS (Founded 1982). Dr. Kritsonis has served as an elementary school teacher, elementary and middle school principal, superintendent of schools, director of student teaching and field experiences, professor, author, consultant, and journal editor. Dr. Kritsonis has considerable experience in chairing PhD dissertations and master thesis and has supervised practicums for teacher candidates, curriculum supervisors, central office personnel, principals, and superintendents. He also has experience in teaching in doctoral and masters programs in elementary and secondary education as well as educational leadership and supervision. He has earned the rank as professor at three universities in two states, including successful post-tenure reviews.
This is the Basic Education Curriculum developed by the Education Department as a guide for teachers handling the subject English. Included are the COMPETENCIES that the learners must acquire in the course of the session
Ace Maths Unit Six: Teaching All Children Mathematics. Reading 1: Guidelines ...PiLNAfrica
This unit explores the implications of the fundamental assumption in this module – that ALL children can learn mathematics, whatever their background or language or sex, and regardless of learning disabilities they may have. It gives practical guidance on how teachers can adapt their lessons according to the specific needs of their learners.
The purpose of this research is produce learning set equipment on heat material of ethnoscience based in Tegal district, The results showed that the feasibility of syllabus-based ethnoscience include into the category is very good because it has a percentage of 96,43%. The feasibility learning device of an ethnoscience-based into a very good category because it has a percentage of 91,37%. Ethnoscience-based learning tool able to improve student learning outcomes from the average value of 42,82 to 80,06 and the gains value 0,65. While the questionnaire of student’s learning interest after the application of physics learning device on ethnoscience based heat material in Kabupaten tegal get the average value 3,01 with the high criteria.
Classification of the Subject Content of BSE Physical Sciences Majors (2015 C...elio dominglos
Undergraduate research about the Course content of Bachelor of Secondary Education - Physical Sciences majors. this covers how much units and what are the courses taken by the physics majors at Benguet State University, year 2015. Since the curriculum was already changed this serves as reference for those who are making there researches specially the secondary education in BSU.
Yager, robert the development of science teacher programs focus v8 n1 2014William Kritsonis
NATIONAL FORUM JOURNALS (Founded 1982 (www.nationalforum.com) is a group of national and international refereed journals. NFJ publishes articles on colleges, universities and schools; management, business and administration; academic scholarship, multicultural issues; schooling; special education; teaching and learning; counseling and addiction; alcohol and drugs; crime and criminology; disparities in health; risk behaviors; international issues; education; organizational theory and behavior; educational leadership and supervision; action and applied research; teacher education; race, gender, society; public school law; philosophy and history; psychology, sociology, and much more. Dr. William Allan Kritsonis, Editor-in-Chief.
Yager, stuart exemplary science teacher education program nftej v 24 n3 2014William Kritsonis
Dr. William Allan Kritsonis, Editor-in-Chief, NATIONAL FORUM JOURNALS (Founded 1982). Dr. Kritsonis has served as an elementary school teacher, elementary and middle school principal, superintendent of schools, director of student teaching and field experiences, professor, author, consultant, and journal editor. Dr. Kritsonis has considerable experience in chairing PhD dissertations and master thesis and has supervised practicums for teacher candidates, curriculum supervisors, central office personnel, principals, and superintendents. He also has experience in teaching in doctoral and masters programs in elementary and secondary education as well as educational leadership and supervision. He has earned the rank as professor at three universities in two states, including successful post-tenure reviews.
This is the Basic Education Curriculum developed by the Education Department as a guide for teachers handling the subject English. Included are the COMPETENCIES that the learners must acquire in the course of the session
Ace Maths Unit Six: Teaching All Children Mathematics. Reading 1: Guidelines ...PiLNAfrica
This unit explores the implications of the fundamental assumption in this module – that ALL children can learn mathematics, whatever their background or language or sex, and regardless of learning disabilities they may have. It gives practical guidance on how teachers can adapt their lessons according to the specific needs of their learners.
The purpose of this research is produce learning set equipment on heat material of ethnoscience based in Tegal district, The results showed that the feasibility of syllabus-based ethnoscience include into the category is very good because it has a percentage of 96,43%. The feasibility learning device of an ethnoscience-based into a very good category because it has a percentage of 91,37%. Ethnoscience-based learning tool able to improve student learning outcomes from the average value of 42,82 to 80,06 and the gains value 0,65. While the questionnaire of student’s learning interest after the application of physics learning device on ethnoscience based heat material in Kabupaten tegal get the average value 3,01 with the high criteria.
There are several misconceptions about the valence shell of the atom. The key questions that arise in the minds of the learners are:
Is valence shell really the outermost shell?
2. Are there only seven shells in an atom?
3. When shells are supposed to be made up of subshells, why can we not represent the subshells in the valence shell structure of the atom?
4. When electrons are said to occur in orbitals, why can we not indicate the orbitals in the valence shell structure?
4. How can we represent the origins for valance band and conduction band in the atomic structure?
5. What are some good metaphors for the core of the atom and the rest of the atom?
Here is a lesson created by Chemistry teachers to address these misconceptions.
Influence of Pre-Service Teachers’ Subject Specialization on their Skills of ...BabayemiJohnOlakunle1
This study examined the influence of pre-service teachers’ subject specialization on their skills for improvisation and management of resources using survey research of expost-facto type. The sample comprised 150 N.C.E pre-service teachers randomly selected from 50 secondary schools in Oyo State. The instruments used were Questionnaire on Assessing Pre-service Teachers’: Skills of Improvisation (r = 0.73); Management of Resources (r = 0.70). Two research questions were raised. The data collected were analyzed using mean, ANOVA and t-test. The result showed that subject specialization had no influence on pre-service teachers’ skills for improvisation and management of resources (F=0.953; P>.05; F=2.536; P>.05).These findings have significant implications for Science teachers and curriculum planners.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
4. Message of the Director General
The first curriculum revision for the new millennium is based on the elimination of the several
problems obtaining in the present education system. The present curriculum reforms have been
planned having identified the problems that youth face consequent to the weakening of their
thinking abilities, social abilities as well as personal abilities and step by step exploration of
factors leading to this situation, to overcome which, the necessary background was prepared.
Compared to the other countries in the Asian region, our country took the lead in education in
earlier years. But most countries in this region have superceded Sri Lanka in education today.
Some factors that influenced this deterioration are the action taken by educational institutions to
continue to take action to confirm the known, learn that which had been decided on earlier, and
reconstruct that which was, in the same form itself.
All these matters have been taken into consideration and the officers of the National Institute of
Education have endeavoured to prepare the new curriculum on the basis of a distinct philosophy.
The primary objective here is to change that which is known, explore that which is new and
develop that which is necessary for tomorrow and build up a generation of students who can
display their readiness for a successful future. But there is no need to reiterate, the need for a
visible change in the teacher’s role for the realization of this objective. In place of the obvious
transactional teacher role presenting in our classrooms so far, the Sri Lankan school teacher will
have to understand and conform to a student-centered, competency based and activity focused
transformational role.
It is our firm belief that this Teacher Instruction Manual will serve you as an aid to become an
effective teacher through the provision of numerous instructions that will help you adapt to the
new situation. Through the study of these instructions you will be provided the opportunity of
making your daily teaching as well as the evaluation task easy. There is no doubt that instructions
for student exploration and other quality inputs will help facilitate the teacher’s task. Similarly,
the Teacher Instruction Manual will help convey to school principals valuable information they
can use in time-tabling, sharing of limited resources and internal supervision.
My sincere thanks go to Dr. Mrs. I. L. Ginige, Assistant Director General (Curriculum
Development) Science & Technology Faculty of National Institute of Education for her direct
involvement in the preparation of this Teacher Instruction Manual that will serve an immense
purpose in the task performed at school level by the section above and also teacher educationist
involved in beginning or continuous teacher educational matters, in-service advisors as well as
officers at various levels, involved in external supervision plus monitoring programmes.
Professor J. W. Wickramasinghe
Director General
National Institute of Education
iii
5. Preface
The first curriculum reform for the millennium implemented with the aim of preparing a
powerful basis for a new Sri Lanka anticipates a visible transformation of the teacher’s role. The
three main sections below are included in the Teacher Instruction Manual prepared with the
objective of providing the teacher with the necessary support in this regard.
· Detailed Syllabus
· Activity Continuum that helps in the implementation of the syllabus
· Instruments for the extension of the learning teaching process.
Teachers have been provided the opportunity of understanding several basic matters that
have been taken into consideration in the preparation of the curriculum for the detailed syllabus
extending beyond subject topics and sub-topics. Competency levels that correspond to subject
competency have been included in this section that commences with an introduction to the factors
and subject aims that formed the basis of the new syllabus. One special features of this section is
that, while the knowledge-base determined under competency level each student needs to develop
has been introduced as the subject content the multiple learning and teaching methods employed
in transmitting this section to the student has also been taken into consideration in determining the
time frame with respect to each competency level.
The final part of the detailed syllabus presented under the heading “School Policy and Programs”
needs to be studied very carefully and understood by every instructional leader. This section
provides school managers a range of valuable instructions to assist them in the allocation for
teaching, subject-teaching assigning functions to teachers, implementing co-curricular activities
as well as supervision of the teacher’s task. The second section of the Teacher Instruction Manual
has been prepared with the objective of providing teachers with clear understanding of the proposed
learning- teaching methodology. This section commences with the introduction of the methods of
planning activities under competency-based education as well as the change in the teacher’s role.
Although the activity continuum necessary for the implementation of the curriculum has been
introduced next, the implementation of the proposed activity in the very same manner is not
expected of teachers. The teacher should endeavor to make use of his / her creative, as well as
critical thinking abilities and adapt these activities in a manner that suits ones class, best. Although
instructions have been provided on the constitution of groups in keeping with the facets of the
problems subject to exploration, the teacher is expected to take an intelligent decision on the
number of groups based on number of students in the class.
iv
6. Time has been allocated for activities to ensure achievement of the relevant competency levels.
Therefore, teachers may have to exceed the 40-minute period. While each activity has been
provided adequate time for the actualization of each competency level, the teacher is expected
to make use of single or double periods in the time table and breakdown these activities, as
suitable in implementing them.
For the success of the procedure it is essential that every time an activity commenced the previous
day is carried over to the following day, that a brief summary of the part of the activity completed
the previous day is presented to the class. Similarly, this decision will provide the school community
with the opportunity of involving students in effective learning where teachers obtain leave of
absence.
The final item in this section is a list of quality inputs necessary for the maintenance of the quality
of subject learning and teaching, when taken as a whole. As such, the teacher has a choice of
ordering out the necessary learning-teaching materials in time and having them on hard.
Included in the third part of the teacher Instruction Manual under the title
“ Assessment and evaluation” are a number of important hints to ensure that the expected results
of the exercise are realized.
This section has been so structured as to introduce matters related to the assessment and evaluation
that should take place under each activity, extension of the learning and teaching that takes place
based on activity groups and the nature of the questions that might be expected in general
examinations. It must be pointed out that the primary responsibility of the teachers is to Identify
instances where assessment and evaluation can be implemented in the course of each activity
and to carry out this task successfully on the basis of common criteria. The set of instruments
prepared with a range of activities as the objective for the purpose of extending learning and
teaching provide students with the opportunity of involvement in continuous learning outside the
recommended classroom sessions. While it is the task of the teacher to regularly examine the
learning students receive, based on these instruments, and encourage them, arriving at a correct
decision regarding the final results of the activities and communicating that decision to the relevant
parties is expected of the teacher. It is essential that a visible change takes place in general
examinations for the success of the learning-teaching process. The National Institute of Education,
with the assistance of the Sri-Lanka Department of Examinations, has introduced several prototype
questions for educational levels that terminate with these examinations. Since this change in
examination question papers has been suggested in order to direct students to learn through
practice and experience, instead of resorting to mechanical approaches like memorizing or
answering model question papers, the education of school students and parents about this change
should commence at the beginning itself.
v
7. All teachers should realize that various activities can be developed for the achievement of any
particular competency level. Accordingly, they should be prepared for more successful teaching
through the use of better approaches, exploration, as well as instruments for the extension of
learning and teaching.
The present Teacher Instruction Manual will give teachers right throughout the country the courage
to effect a visible change in the teacher’s role and prevent their becoming inactive in the presence
of new approaches. Similarly, we expect to award certificates and provide numerous development
opportunities to teachers who go beyond the activities to involve themselves in the innovation of
novel creations. What teachers have to do order in to become eligible to the awards is to improve
these activities, using their creative thinking, and present them. Learning-teaching plans prepared
in this manner outside the basic activity plan, should be forwarded to Assistant Director General
( Curriculum Development ), Science and Technology faculty, National Institute of Education,
Sri Lanka. Selection of those entitled to awards will be made subsequent to the study of these
activities by the relevant subject committees.
We have endeavoured in this manner, to bring learning-teaching assessment and evaluation on to
the same platform through new methodologies. According to this, teachers will be provided
substantial latitude to meaningfully handle the learning-teaching process, school-based assessment,
as well as assignment of home-work. It is our firm conviction that the school system of Sri Lanka
will, make maximum use of this aid and depart from orthodox learning-teaching approaches to
enhance the thinking abilities, social abilities as well as the individual abilities of the sons and
daughters of the county.
Dr. Indira Lilamani Ginige
Assistant Director General (Curriculum Development),
Faculty of Science and Technology ,
National Institute of Education,
Sri Lanka.
vi
8. Direction: Prof. J W Wickremasinghe - Director General
Guidance: Dr. I. L. Ginige
Assistant Director General
Faculty of Science and Technology
National Institute of Education
Supervision : Mr. C M R Anthony
Director
Department of Science, Health & Physical Education
Instructional leadership, Co-ordination and Editing :
Mr. C M R Anthony - Director
Mr. G H Gauthamadasa - Chief Project Officer
Mr. W A D Rathnasuriya - Chief Project Officer
Mr. W A Sumathipala - Project Officer
Ms.J Athamlebbe - Project Officer
Mr. A D A de Silva - Project Officer
Mr. L K Waduge - Project Officer
Mr. P Malavipathirana - Project Officer
Ms. Nadee Ama Jayasekera - Project Officer
Ms. H M Mapagunaratne - Asst. Project Officer
Translation : Mr. R.B.A.Jayasekara
Computer page setting : Mr. K.Wimalasena, Mahinda College, Galle.
Art : Ms. U L N Fernando
Teacher Service,
Sirimavo Bandaranayake BV. Colombo.07.
Cover page and pictures : Master. Soraj Dhananjaya Kolonne,
Grade 11, Thurstan College, Colombo.
vii
15. High Voltage
Anode
Cathode with a slit
production of possitive rays
Neutron
Possitively charged particles named α particles are emitted from radio active sources.When
fall on to the instrument to detect charged particals, it causes a deflection.(Fig. a)
In 1932 James Chadwick conducted an experiment form which it was founded that when a
thin Berylium sheet was place in between the radio active source and the detector no deflection
was seen ( Fig. b)
When a paraffin sheet was place between the Berylium sheet and the detector tere was a
α
deflection. (Fig. c)
Source of
Detector
particals
Shows deflection
(a) Possitive charge
particals fall on
detector
Berylium plate
No deflection is
shown
(b)
charged particals are
not falling on the
Berylium plate Paraffin wax plate detector
Shows a deflection
(c) charged particals
fall on the detector
particals Chargeless Neutrons Particals with possitive charge
(d)
14
24. Atomic Number
The atomic number of an element is the number of protons in the atom of that element.(In a
neutral atom the number of protons in the nucleus is equal to the number of electrons in the
shells.)
Mass number
The mass number of an element is the sum of the protons and neutrons in the atomic nucleus
of that element,
Relative atomic Mass
You could understand that atoms are particles having a very small mass hence it is not useful
in Chemistry to use the international unit of mass,the kilogram in relation to the mass of an
atom. Hence the mass of an atom is stated as a relative value of a standard unit.It is called the
Relative atomic mass unit.
12
Relative atomic mass Unit = mass of 6 C Isotope atom
12
The relative atomic mass of an atom is the number of times the mass of that atom in relation to
the relative atomic mass unit.It could be stated as
Relative atomic mass = mass of an atom
atomic mass unit
Relative atomic mass = mass of an atom of an element
12
mass of an atom of 6 C isotope x 1/12
There are differences between the atoms of the same element.An example of this is the presence
of atoms of elements with same number of protons but with different number of neutrons,Such
elements where the number of protons in the atomic nucleus is the same but the number of
neutrons vary,and as a result they vary in their mass number.These are called isotopes.
A Symbol is used to identify an atom.In an atomic symbol at the top left is the mass number
12
and at the bottom is the atomic number( 6 C)
23
25. Annex 1.2.6
Data about some of the isotopes found in nature of some elements
Name of Atomic Mass Symbol of Number of Number of Number of
element number number the isotope protons Neutrons Electrons
in the in the in the
nucleus nucleus nucleus
Hydrogen 1 1 1
H 1 0 1
1
1 2 2
1 H 1 1 1
1 3 3
1 H 1 2 1
3
Helium 2 3 2 He 2 1 2
2 4 4
2 He 2 2 2
Lithium 3 6 6
3 Li 3 3 3
3 7 7
Li 3 4 3
3
10
Boron 5 10 5 B 5 5 5
5 11 11
5 B 5 6 5
Carbon 6 12 12
6 C 6 6 6
6 13 13
C 6 7 6
6
14
Nitrogen 7 14 7 N 7 7 7
7 15 15
7 N 7 8 7
16
Oxygen 8 16 8 O 8 8 8
17
8 17 8 O 8 9 8
8 18 18
8 O 8 10 8
20
Neon 10 20 10 Ne 10 10 10
21
10 22 10 Ne 10 11 10
10 22 22
10 Ne 10 12 10
Sulpher 16 32 32
S 16 16 16
16
16 33 33
S 16 17 16
16
16 34 34
S 16 18 16
16
24