Recent Changes

Sunday, September 10

  1. page 6. Electrons and bonding edited ... Bonding in a Nutshell {CW bonding in a nutshell 052012.pdf} Electron pairing {electron pairi…
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    Bonding in a Nutshell {CW bonding in a nutshell 052012.pdf}
    Electron pairing {electron pairing as magnets 082117.pdf} ... a paper folding project ... while this is at best an approximation, it
    illustrates thatthe magnetic properties
    ...
    an orbital mitigatesreduce the
    electrostatic repulsion.
    Video tutorial on...
    (view changes)
    9:35 pm
  2. page 6. Electrons and bonding edited ... Aufbau principle animation - filling the atomic orbitals Bonding in a Nutshell {CW bonding in…
    ...
    Aufbau principle animation - filling the atomic orbitals
    Bonding in a Nutshell {CW bonding in a nutshell 052012.pdf}
    Electron pairing in an orbital{electron pairing as magnets 082117.pdf} ... a
    illustrates that magnetic properties of electrons and how pairing electrons in an orbital mitigates the
    electrostatic repulsion.
    (view changes)
    9:33 pm
  3. page 6. Electrons and bonding edited ... Aufbau principle animation - filling the atomic orbitals Bonding in a Nutshell {CW bonding in…
    ...
    Aufbau principle animation - filling the atomic orbitals
    Bonding in a Nutshell {CW bonding in a nutshell 052012.pdf}
    Electron pairing in an orbital ... a paper folding project ... while this is at best an approximation, it
    illustrates that magnetic properties of electrons and how pairing electrons in an orbital mitigates the
    electrostatic repulsion.

    Video tutorial on...
    Covalent bonding and Lewis Structure Poweroint {Covalent bonds and Lewis structures 052112.pps}
    (view changes)
    9:25 pm

Sunday, March 19

  1. page 8. Electrochemistry edited In this chapter we will learn about oxidation-reductions reactions and electrochemistry. {http://w…
    In this chapter we will learn about oxidation-reductions reactions and electrochemistry.
    {http://www.lab-initio.com/screen_res/nz220.jpg}
    Things to know about oxidation-reduction reactions. {Things to Know About Oxidation Reduction reactions 032612.pdf}
    Reference material on electrochemistry
    Lots of good information on batteries here.
    (view changes)
    12:54 pm

Tuesday, November 11

  1. page Valence and oxidation number edited ... Electronegativity is defined as "a measure of the ability of an atom to attract shared pa…
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    Electronegativity is defined as "a measure of the ability of an atom to attract shared pairs of electrons."
    Table of electronegativities.
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    of content in the first few paragraphs above was
    (view changes)
    8:10 pm
  2. page Valence and oxidation number edited ... number, is a measure of the maximum number of Over the last century, the concept of vale…
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    number, is a measure of the maximum number of
    Over the last century, the concept of valence evolved into a range of approaches for describing the chemical bond, including Lewis structures (1916), valence bond theory (1927), molecular orbitals (1928), valence shell electron pair repulsion theory (1958) and all the advanced methods of quantum chemistry.
    The etymology of the word "valence" traces back to 1425, meaning "extract, preparation," from Latin valentia "strength, capacity," and the chemical meaning referring to the "combining power of an element" is recorded from 1884, from German Valenz.
    ...
    In the period table the Roman numerals tell us the valence of the elements in that column. The term valence refers to the "combining power" of the element and tells the number of bonds the element could form with a halide.
    ...I..........II...........III.........IV.........V..........VI.......VII*....
    ...
    -- CaCl2 ---- GaCl3 -- GeCl4-- AsC l5AsCl5 -- SeF6
    ...
    --- TiCl4 -------- VF5 -----
    The greatest number of fluorine atoms that a single chlorine atom will bond with is 5, BrF5. But iodine, also in column VII will bond with seven fluorine atoms, IF7.
    In MnF4 manganese doesn't have a combining power of 7, but it does in Mn2O7. Also, rhenium forms ReF7.
    While the word "valence" still has many uses in chemistry, we seldom use it within the context of "combing power", or expressing the number of bonds an element can form.
    Because of the ambiguity of the term valence ,we now use the system of oxidation numbers as used in Stock nomenclature for coordination compounds, and the lambda notation, as used in the IUPAC nomenclature of inorganic chemistry . The "oxidation state" is a more clear indication of the electronic state of atoms in a molecule. The "oxidation state" of an atom in a molecule gives the number of valence electrons it has hypothetically gained or lost, by imagining the bonds to be completely ionic. In contrast to the valence, the oxidation state can be positive or negative.
    ...
    and oxidation statess.states {Valence Concept and Oxidation States 021012.pdf} .
    Oxidation is the chemical process in which an element combines with oxygen to form an "oxide". The "oxidation state" refers to the relative number of oxygen atoms which combine with the element. For instance, the metal tin can combine with oxygen to form two compounds SnO and SnO2. Since in SnO2 tin is combined with twice as many oxygen atoms, it has a greater oxidation state. If we assign an oxidation state of -2 to oxygen, the tin in SnO has an oxidation state of +2, and in SnO2 tin has an oxidation state of +4.
    ...
    is the "increase in oxidation state." In some cases there is an actual or
    ...
    or more electrons.electrons in oxidation. In forming
    ...
    in SnO2. In reality, the bonds in SnO and SnO2 are largely covalent, and there is no actual loss of electrons, only a change in oxidation state.
    Summary
    1. Atoms form chemical bonds with other atoms to make compounds.
    (view changes)
    8:09 pm

Thursday, February 6

  1. page 10. Nuclear chemistry edited ... History of atomic theory concept map {Atomic_theory_concept_map_101109.pdf} Atoms - "ev…
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    History of atomic theory concept map {Atomic_theory_concept_map_101109.pdf}
    Atoms - "everything you need to know" concept map {CW_atoms_info_101009.pdf}
    ...
    nuclear decay {CW Types of Nuclear Decay 011708 051709-2.pdf}
    Isotopes Powerpoint {Chpt _4 - Isotopes 022609.pps}
    Isotopes worksheet {CW atomic theory nuc chem 022105 051212.pdf} and table {CW isotope table 051212.pdf}
    (view changes)
    10:36 pm
  2. page 10. Nuclear chemistry edited ... History of atomic theory concept map {Atomic_theory_concept_map_101109.pdf} Atoms - "ev…
    ...
    History of atomic theory concept map {Atomic_theory_concept_map_101109.pdf}
    Atoms - "everything you need to know" concept map {CW_atoms_info_101009.pdf}
    ...
    nuclear decay {CW Types of Nuclear Decay 011708 051709.doc}
    Isotopes Powerpoint {Chpt _4 - Isotopes 022609.pps}
    Isotopes worksheet {CW atomic theory nuc chem 022105 051212.pdf} and table {CW isotope table 051212.pdf}
    (view changes)
    10:33 pm

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