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  2. BBC Bitesize - Wikipedia

    en.wikipedia.org/wiki/BBC_Bitesize

    GCSE Bitesize was launched in January 1998, covering seven subjects. For each subject, a one- or two-hour long TV programme would be broadcast overnight in the BBC Learning Zone block, and supporting material was available in books and on the BBC website. At the time, only around 9% of UK households had access to the internet at home.

  3. Key Stage 2 - Wikipedia

    en.wikipedia.org/wiki/Key_Stage_2

    Key Stage 2 is the legal term for the four years of schooling in maintained schools in England and Wales normally known as Year 3, Year 4, Year 5 and Year 6, when the pupils are aged between 7 and 11 years.

  4. GCSE Science - Wikipedia

    en.wikipedia.org/wiki/GCSE_Science

    Triple Award Science, commonly referred to as Triple Science, results in three separate GCSEs in Biology, Chemistry and Physics and provide the broadest coverage of the main three science subjects. The qualifications are offered by the five main awarding bodies in England; AQA , Edexcel , OCR , CIE and Eduqas .

  5. Chemistry - Wikipedia

    en.wikipedia.org/wiki/Chemistry

    Chemistry is the scientific study of the properties and behavior of matter. [1] It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances.

  6. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    A chemical bond is an attraction between atoms. This attraction may be seen as the result of different behaviors of the outermost or valence electrons of atoms. These behaviors merge into each other seamlessly in various circumstances, so that there is no clear line to be drawn between them.

  7. Reaction rate constant - Wikipedia

    en.wikipedia.org/wiki/Reaction_rate_constant

    where A and B are reactants C is a product a, b, and c are stoichiometric coefficients,. the reaction rate is often found to have the form: = [] [] Here ⁠ ⁠ is the reaction rate constant that depends on temperature, and [A] and [B] are the molar concentrations of substances A and B in moles per unit volume of solution, assuming the reaction is taking place throughout the volume of the ...

  8. Iodine clock reaction - Wikipedia

    en.wikipedia.org/wiki/Iodine_clock_reaction

    2 s 2 o 2− 3 + i 2 → s 4 o 2− 6 + 2 i − After some time the solution changes color to a very dark blue, almost black. When the solutions are mixed, the second reaction causes the iodine to be consumed much faster than it is generated , and only a small amount of iodine is present in the dynamic equilibrium .

  9. VSEPR theory - Wikipedia

    en.wikipedia.org/wiki/VSEPR_theory

    Another example is O(SiH 3) 2 with an Si–O–Si angle of 144.1°, which compares to the angles in Cl 2 O (110.9°), (CH 3) 2 O (111.7°), and N(CH 3) 3 (110.9°). [24] Gillespie and Robinson rationalize the Si–O–Si bond angle based on the observed ability of a ligand's lone pair to most greatly repel other electron pairs when the ligand ...