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4_73calcs01ram updated Jan 17th 2008 |
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On-line chemistry CALCULATIONS for KS4 Science, GCSE Chemistry and AS Chemistry (basic calculations) EMAIL query?comment or request for type of GCSE calculation?
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Every atom has its own unique atomic
mass based on a standard comparison or relative scale
e.g. it has been based on hydrogen H = 1, oxygen O = 16. The relative atomic
mass scale is now based on an isotope of carbon,
carbon-12, However there are complications due to isotopes and so very accurate atomic masses are not whole numbers. Isotopes are atoms of the same element with different masses due to different numbers of neutrons. The very accurate atomic mass scale is based on a specific isotope of carbon, carbon-12, 12C = 12.0000 units exactly, for most purposes C = 12 is used for simplicity. For
example The strict definition of relative atomic mass (Ar) is that it equals average mass of all the isotopic atoms present in the element compared to 1/12th the mass of a carbon-12 atom. Examples of relative atomic mass calculations
The mass number for any isotope is the sum of the protons and neutrons in the nucleus, and is always a whole number. (AS/A2 students only) Relative
isotopic mass
= the accurate mass of a single isotope of
an element compared to 1/12th the mass of a
carbon-12 atom e.g. the accurate mass of If we were to redo the chlorine example 1.1 above, which is quite adequate for GCSE purposes, more accurately at A level, we would do .... chlorine is 75.77% 35Cl of isotopic mass 34.9689 and 24.23% 37Cl of isotopic mass 36.9658 so Ar(Cl) = [(75.77 x 34.9689) + (24.23 x 36.9658)] / 100 = 35.4527 (but 35.5 is usually ok in calculations pre-university!) See also Mass Spectrometer and isotope analysis on the GCSE-AS(basic) Atomic Structure Notes.
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,
which is given the value of 12.0000 amu. (*
The letter A on its own usually means the mass number of a particular isotope)
, 
and 
are
the three isotopes of hydrogen, though the vast majority of hydrogen atoms have
a mass of 1. When their accurate isotopic masses, and their % abundance are
taken into account the average accurate relative mass for hydrogen =
1.008, but for most purposes H = 1 is good enough! 
is 58.9332!
H
H
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4_73calcs01ram updated Jan 17th 2008 |
These chemical calculations pages of revision notes will also prove useful for basic revision for students studying revising tutoring teaching Advanced Level GCE AS A2 IB CHEMISTRY courses in unofficial support the Chemistry in any advanced-subsidiary AQA, EDEXCEL, OCR, CIE, WJEC, SQA and CCEA (NI) UK or Cambridge/London/Edexcel International and OCR/CIE International examinations.
ks4 science examinations gcse-igcse chemistry revision * ks4 science examinations-gcse-igcse chemistry revision * ks4 science examinations-gcse-igcse chemistry revision * ks4 science examinations-gcse-igcse chemistry revision * ks4 science examinations-gcse-igcse chemistry revision * ks4 science examinations-gcse-igcse chemistry revision * SITE PURPOSE EDUCATION - online learning or 'self-private-tuition' using revision notes, quizzes, practice tests involving GCSE Science CHEMISTRY in the areas of REVISING only the CHEMISTRY-Earth Science-Radioactivity at Doc Brown's Chemistry Clinic via HOMEPAGE in secondary school/schools, 6th form college/colleges, academy/academies or home self-study. Hopefully it will encourage interest and understanding of Chemistry, Earth Science and Radioactivity in any country of the world, though the site is written entirely in English. The website is designed to help and unofficially support students/teachers revise-learn/teach the chemistry for modular or co-ordinated examination science courses from UK QCA based AQA, OCR (Oxford and Cambridge) Twenty First (21st) Century and Gateway Science, Edexcel 360Science , Nuffield, Salters, Cambridge International (CIE), London International, WJEC, CCEA exams etc. Also, national award assessments-examinations for GCSE-IGCSE-KS4-O level-BTEC-NVQ applied, additional and chemistry national science courses. Also covers, mainly via quizzes the UK National KS3 SATs Science-biology/chemistry/physics (SAT revision levels 3-5 or 5-7) and covers much of the revising, learning and teaching chemistry examinations for the national curriculum for secondary schools and colleges. The site does not support the content of England, Wales or Northern Ireland primary science KS1 or KS2. The notes should also provide some background theory for a coursework assignment or project. BUT please note that my on-line revision notes and quizzes are no substitute for good classroom teaching-lecturing and thorough studying of your own notes and textbooks, practicing past papers and a copy of the syllabus which are readily downloaded from the examination board sites, but I hope here and there they will lend a tutoring hand on some topic, unit, module etc. For final revision you have to be intellectually honest about what you don't know or follow, YOU have to take the stuff to pieces, analyse what you do/do not understand and reconstruct it so it all makes sense in the end. There is no other way, there are no magic secrets on how to revise and learn, its mainly down to hard work and just good old fashioned study and employing teach-yourself strategies without the need for extra tutors and tutoring lessons. I also think there is too much hit and miss revision using past papers (which I do NOT supply) and not enough systematic revision. I also hope it will help teachers in planning lessons and developing schemes of work for science-chemistry. There are no lesson plans on the site but there are plenty of quizzes to incorporate into classroom activities whether photocopied or on electronic whiteboard projector for use as self-tuition-assessment purposes and a variety of teaching and learning styles and the images may be used in Microsoft Word documents and powerpoint projections. The site seems to be used by a large number of home study tutors, particularly the revision notes. An individual tutor may print out the notes for science-chemistry learning teaching-tuition purposes and for background material for assignments and projects. I have no interest or time in producing WORD.doc or xxxx.pdf files of the notes at the moment. Neither have I time to write up many practical laboratory experiments ('lab'-'labs') at the moment, but the notes contain lots of background information of chemical reactions in terms of observations-balanced equations-reactants-products-theory etc. I also find it difficult to recommend specific exam websites or syllabus textbooks, it depends exactly on what you need, what you have time for, and there are so many of them to choose from and I do not supply past examination papers for classes. The sites resources include revision notes, quizzes and worksheets which provide support for home study or tuition for homework and coursework help e.g. science investigations for any of the key stage courses indicated, but I do not supply lesson plans. Dr W P Brown gcse 10-11-2007 * ks4 science examinations gcse-igcse chemistry revision * ks4 science examinations-gcse-igcse chemistry revision * ks4 science examinations-gcse-igcse chemistry revision * ks4 science examinations-gcse-igcse chemistry revision * ks4 science examinations-gcse-igcse chemistry revision * ks4 science examinations-gcse-igcse chemistry revision