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docb4_72bond updated April 6th 2008 |
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GCSE-IGCSE KS4 Science-CHEMISTRY and AS (basic) Chemistry Revision-Information Notes on The Structure and properties of substances - Ionic, Covalent & Metallic Bonding Part 1 Introduction - why do atoms bond together? (this page, read first) and sub-index for Parts 2-5 (this page) Part 2 Ionic Bonding - compounds and properties Part 3 Covalent Bonding -small simple molecules and properties Part 4 Covalent Bonding - macromolecules and giant covalent structures Part 5 Metallic Bonding - structure and properties of metals Part 6 More advanced concepts for advanced level chemistry (in preparation) * Keywords/phrases/names sub-index for Parts 2-5: Examples of ionic compounds described: sodium chloride NaCl (exemplar for any Li/Na/K + F/Cl/Br/I combination), magnesium chloride MgCl2 (exemplar for any Mg/Ca + F/Cl/Br combination), aluminium fluoride AlF3, potassium oxide K2O (exemplar for any Li/Na/K + O/S combination), magnesium/calcium oxide MgO/CaO and magnesium/calcium sulphide (MgS/CaS), aluminium oxide Al2O3 (exemplar for Al2S3) * Examples of covalent molecules: simple small molecule bonding e.g. water * physical properties of small molecules * giant network bonding - giant molecules e.g. carbon C-diamond/graphite, silicon Si/silica SiO2 * properties of giant covalent structures * polymers/plastics * properties of polymers * inter/intra (internal)-molecular forces * hydrogen H2, chlorine Cl2, hydrogen chloride HCl, water H2O, ammonia NH3, methane CH4, oxygen O2, carbon dioxide CO2, ethene C2H4, nitrogen N2, ethane C2H6, chloromethane CH3Cl, methanol CH3OH, carbon (diamond), carbon (graphite), carbon (buckminsterfullerene/fullerenes), silica/silicon dioxide SiO2 * examples of ionic compounds * physical properties of ionic compounds *If your ionic compound is not listed, look for a compound with a similar formula and you should be able to work it out from the example given. The use of the word exemplar implies you are dealing with the same set of outer electron arrangements (configurations), which is why you can work out lots more dot and cross diagrams of ionic compounds by understanding one example * metal bonding model element/alloys * physical properties of metals *
Some atoms are very reluctant to combine with other atoms and exist in the air around us as single atoms. These are the Noble Gases and have very stable electron arrangements e.g. 2, 2,8 and 2,8,8 because their outer shells are full. The first three are shown in the diagrams below and explains why Noble Gases are so reluctant to form compounds with other elements.
All other atoms therefore, bond together to become electronically more stable, that is to become like Noble Gases in electron arrangement. Bonding produces new substances and usually involves only the 'outer shell' or 'valency' electrons and atoms can bond in two ways. The phrase CHEMICAL BOND refers to the strong electrical force of attraction between the atoms or ions in the structure. The combining power of an atom is sometimes referred to as its valency and its value is linked to the number of outer electrons of the original uncombined atom (see examples later). (a) IONIC BONDING - By one atom transferring electrons to another atom to form oppositely charged particles called ions which attract each other - the ionic bond.
If a particle, as in a neutral atom, has equal numbers of protons (+) and electrons (-) the particle charge is zero The proton number in an atom does not change BUT the number of associated electrons can! If negative electrons are lost If negative electrons are gained The charge on the ion is numerically related to the number of electrons transferred i.e. electrons lost or gained. For any atom or group of atoms, for every electron gained you get a one unit increase in negative charge on the ion, for every electron lost you get a one unit increase in the positive charge on the ion. The atom losing electrons forms a positive ion (cation) and is usually a metal. (b) COVALENT BONDING - sharing electrons to form molecules with covalent bonds, the bond is usually formed between two non-metallic elements in a molecule. The two positive nuclei (due to the positive protons in them) of both atoms are mutually attracted to the shared negative electrons between them - the covalent bond. They share the electrons in a way that gives a stable Noble Gas electron arrangement. (c) METALLIC BONDING isn't quite like ionic or covalent bonding, the metal atoms form positive ions, but no negative ion is formed from the same metal atoms, but the positive metal ions/atoms are attracted together byt the free moving negative electrons between them. NOBLE GASES are very reluctant to share, gain or lose electrons to form a chemical bond. They are already electronically very stable. For most other elements the types of bonding and the resulting properties of the elements or compounds are described in detail in Parts 2 to 5. In all the electronic diagrams ONLY the outer electrons are shown.
ks4 national curriculum science examinations e-gcse-igcse chemistry revision * ks4 national curriculum science examinations-gcse-igcse chemistry revision * ks4 national curriculum 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 curriculum science courses. 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. * ks4 science examinations e-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 * Dr W P Brown Feb 15th 2008
Online free help resources for Key Stage 4 AQA, Edexcel, OCR, CIE GCSE IGCSE BTEC Science, GCE, AS, A2 Advanced subsidiary Chemistry A levels, IB Diploma and US K12 (K-12 grades) courses and examinations and revising for the various syllabuses and specifications. Exploring the site for lessons, plans, ideas for projects and coursework, professional development. Through hard work the site has been built up over the course of many years with no need of special pc software except FrontPage and Hot Potatoes (uvic) for quizzes and worksheets. It is used in the classroom, home learning-tutoring-schooling and guidance, private tuition, school retakes revision. Whether you are a teacher/tutor teaching, a student studying, using the pages as self-study guides for your science-chemistry studies etc. etc. I hope the site supports your endeavour. 15-12-07 © Dr W P Brown
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(atomic number) electron arrangement