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    i need help with a few questions i have draw out the dot and cross diagrams but:

    1) what shape would you expect a tetrachloromethane molecule, CCl4 to have? Explain your answer

    2) how many pairs of electrons are there around the central S atom in a molecule of hydrogen sulfide, H2S? What shape would you expect this molecule to have?

    3) sulphur trioxide is a planar molecule, explain how electron pair repulsion theory predicts the shape.
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    (Original post by MrMoonmunch)
    i need help with a few questions i have draw out the dot and cross diagrams but:

    1) what shape would you expect a tetrachloromethane molecule, CCl4 to have? Explain your answer

    2) how many pairs of electrons are there around the central S atom in a molecule of hydrogen sulfide, H2S? What shape would you expect this molecule to have?

    3) sulphur trioxide is a planar molecule, explain how electron pair repulsion theory predicts the shape.
    1) VSEPR theory, C used all 4 electrons for bonding, no lone pairs around C, think what shape is CH4 methane?

    2) H2S, S has 6 valence electrons, 2 H means 1 electron from each, can only form 2 single S-H bonds, that means S use 2 of its electrons for bonding, it has 4 e left, that is 2 non bonding pairs. Think H2O molecule.

    3) VSEPR states, in terms of repulsion, LP/LP > BP/LP > BP/BP
    ie think of AlH3, no lone pair around Al, hence it is trigonal planar.
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    (Original post by MrMoonmunch)
    i need help with a few questions i have draw out the dot and cross diagrams but:

    1) what shape would you expect a tetrachloromethane molecule, CCl4 to have? Explain your answer

    2) how many pairs of electrons are there around the central S atom in a molecule of hydrogen sulfide, H2S? What shape would you expect this molecule to have?

    3) sulphur trioxide is a planar molecule, explain how electron pair repulsion theory predicts the shape.
    1) tetrahedral shape as it has 4 bond pairs and no lone pairs
    2) 4 pairs as 4*2=8e which is a full outer shell
    3) SO3 6 bond pairs, the pairs have forces of repulsion which causes the maximum amount of distance between them
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    Which board are you doing? Because depending on the board they'll want different angles - for salters you say that all electron pairs repel equally to achieve the lowest energy positio where they are most spread out in space (whether they're lone or bonded) and so to work out the shape of your molecule you simply have to count the number of electron pairs around the central atom.

    If there are 2 groups (e.g. CO2) then the angle is 180 and the shape is linear
    There are 3 pairs the shape is trigonal planar and the angle is 120
    for 4 paris it's a bit trickier, but for salters the angles are all 109:
    - with no lone pairs the shape is tetrahedal (e.g. CCl4)
    - with one lone pair the shape is trigonal pyramedal
    - with two unbonded pairs the shape is bent (e.g. H2S)
    For 5 pairs of electrons the shape is trigonal bipyramedal (like two pyramids on top of each other) and the angles are 120 and 90
    For 9 groups of electrons the shape is octahedral and the angles are all 90.

    If you apply these rules to every case it's the simplest way to answer any shapes of molecules question...

    Is that clearly written??
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    (Original post by Dora the Dagger)
    Which board are you doing? Because depending on the board they'll want different angles - for salters you say that all electron pairs repel equally to achieve the lowest energy positio where they are most spread out in space (whether they're lone or bonded) and so to work out the shape of your molecule you simply have to count the number of electron pairs around the central atom.

    If there are 2 groups (e.g. CO2) then the angle is 180 and the shape is linear
    There are 3 pairs the shape is trigonal planar and the angle is 120
    for 4 paris it's a bit trickier, but for salters the angles are all 109:
    - with no lone pairs the shape is tetrahedal (e.g. CCl4)
    - with one lone pair the shape is trigonal pyramedal
    - with two unbonded pairs the shape is bent (e.g. H2S)
    For 5 pairs of electrons the shape is trigonal bipyramedal (like two pyramids on top of each other) and the angles are 120 and 90
    For 9 groups of electrons the shape is octahedral and the angles are all 90.

    If you apply these rules to every case it's the simplest way to answer any shapes of molecules question...

    Is that clearly written??
    You mean 6?
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    (Original post by shengoc)
    You mean 6?
    Haha yes.

    Sorry about that!
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    I genuinely though this said shapes of monocles
    its too late and i have C4 in the morning
    night all
 
 
 
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