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    (Original post by gooner1886)
    Re. decimal places - they usually tell you how many they want e.g. when calculating RAM they say "answer to 1 decimal place"

    For the moles questions I would say its a safe bet to give your answers to 3 significant figures. They have penalised less than 3 in the past
    Thank you! I've kept a note of it
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    Has graphene appeared on the spec and if it has what the hell is it?

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    (Original post by Chewy29)
    Has graphene appeared on the spec and if it has what the hell is it?

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    If I remember the question correctly it does say it's pretty much life graphite? And that it has a high melting point and conducts electricity?

    Just write down what you would do for graphite i.e. Macromolecular, has very strong bonds, these strong bonds must be overcome/broken, which requires a high amount of heat energy.

    Conducts electricity because it has layers with delocalised electrons between them which allow current to flow.
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    I'm doing this on Thursday too

    Can anyone explain the difference in the second and first ionisation energies...

    I just generally don't get it



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    (Original post by gooner1886)
    If I remember the question correctly it does say it's pretty much life graphite? And that it has a high melting point and conducts electricity?

    Just write down what you would do for graphite i.e. Macromolecular, has very strong bonds, these strong bonds must be overcome/broken, which requires a high amount of heat energy.

    Conducts electricity because it has layers with delocalised electrons between them which allow current to flow.
    okay. Thankyou

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    (Original post by gooner1886)
    If I remember the question correctly it does say it's pretty much life graphite? And that it has a high melting point and conducts electricity?

    Just write down what you would do for graphite i.e. Macromolecular, has very strong bonds, these strong bonds must be overcome/broken, which requires a high amount of heat energy.

    Conducts electricity because it has layers with delocalised electrons between them which allow current to flow.
    It's on the june 2012 past paper if you want to check
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    (Original post by x-Sophie-x)
    I'm doing this on Thursday too

    Can anyone explain the difference in the second and first ionisation energies...

    I just generally don't get it



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    First IE - you're removing the outer e- from a neutral atom e.g. A = atom
    A(g) --> A+(g) + e-
    On the left is the neutral atom, on the right is what is formed - a positive ion with the charge +1 and one e-

    Second IE - you're removing the next e- after the one you've just removed so from a positive (+1) ion.
    A+(g) --> A2+(g) + e-
    Left: Positive ion
    Right: What is formed when you remove another e- from the positive ion.

    Hope that kinda made some sense :3 Bad at explaining lol

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    (Original post by Paulineuh)
    First IE - you're removing the outer e- from a neutral atom e.g. A = atom
    A(g) --> A+(g) + e-
    On the left is the neutral atom, on the right is what is formed - a positive ion with the charge +1 and one e-

    Second IE - you're removing the next e- after the one you've just removed so from a positive (+1) ion.
    A+(g) --> A2+(g) + e-
    Left: Positive ion
    Right: What is formed when you remove another e- from the positive ion.

    Hope that kinda made some sense :3 Bad at explaining lol

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    Oh no I understand that, sorry Thank you anyway

    What I meant was, I don't understand those questions where they ask why the second ionisation energy of sodium is say lower than the first ionisation energy of magnesium or something like that..
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    (Original post by x-Sophie-x)
    I'm taking this exam for the first time. Because our stupid school insists we get better results if we do both units in the summer Urgh!

    I hate periodicity the most

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    Periodicity Summarised for you

    Period 3:
    Atomic Radius:
    • Decreases across period
    • Due to more and more protons in nucleus/increasing nuclear charge
    • Electron shielding stays constant


    Melting/Boiling Points:
    • Increases from Na-Al due to stronger and stronger metallic bonds (explain)
    • Silicon has highest MP/BP in period 3 because it is a giant covalent structure
    • Sulfur has a greater MP/BP than Phosphorus because Sulfur exists as S8 and Phosphorus exists as P4
    • van der Waals attraction increases in strength with size
    • Phosphorus has a higher MP/BP than Chlorine for same reason (Cl2)


    1st IE:
    • General trend is for the exact same reasons as atomic radius except this time it is increasing rather than decreasing
    • Al has a lower 1st IE than Mg because it's outermost electron is in the 3p subshell which is further away than the 3s subshell where the outermost electron of Mg lies
    • This means the outermost electron of Al is further away from the nucleus than Mg's outermost electron so will be easier to remove
    • Sulfur has a lower first IE than Phosphorus because in Phosphorus each of the three 3p orbitals have only one electron in them
    • In sulfur one of the 3p orbitals contains two electrons
    • The repulsion between these two electrons makes it easier to remove one


    That is pretty much all you need to know in terms of content for periodicity. However AQA expect you to be able to apply this knowledge to other situations. They may ask about other periods or 2nd/3rd ionisation energies so make sure you understand these principles. Hope that helped
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    (Original post by Sharif Chowdhury)
    Periodicity Summarised for you

    Period 3: Atomic Radius:
    • Decreases across period
    • Due to more and more protons in nucleus/increasing nuclear charge
    • Electron shielding stays constant


    Melting/Boiling Points:
    • Increases from Na-Mg due to stronger and stronger metallic bonds (explain)
    • Silicon has highest MP/BP in period 3 because it is a giant covalent structure
    • Sulfur has a greater MP/BP than Phosphorus because Sulfur exists as S8 and Phosphorus exists as P4
    • van der Waals attraction increases in strength with size
    • Phosphorus has a higher MP/BP than Chlorine for same reason (Cl2)


    1st IE:
    • General trend is for the exact same reasons as atomic radius except this time it is increasing rather than decreasing
    • Al has a lower 1st IE than Mg because it's outermost electron is in the 3p subshell which is further away than the 3s subshell where the outermost electron of Mg lies
    • This means the outermost electron of Al is further away from the nucleus than Mg's outermost electron so will be easier to remove
    • Sulfur has a lower first IE than Phosphorus because in Phosphorus each of the three 3p orbitals have only one electron in them
    • In sulfur one of the 3p orbitals contains two electrons
    • The repulsion between these two electrons makes it easier to remove one


    That is pretty much all you need to know in terms of content for periodicity. However the AQA expect you to be able to apply this knowledge to other situations. They may ask about other periods or 2nd/3rd ionisation energies so make sure you understand these principles. Hope that helped
    That was extremely helpful. Thank you!
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    Could someone explain to me how shells are filled up using Indium as an example?
    Does the 4th shell have an f block (14?)?

    So if we went up to the 6th shell would it be:

    1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 ...

    What comes next?
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    (Original post by x-Sophie-x)
    That was extremely helpful. Thank you!
    You're welcome. I made a teensy mistake in the Melting/Boiling points part. The MP/BP increases from Na to Al not Na to Mg. My apologies
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    (Original post by Sharif Chowdhury)
    You're welcome. I made a teensy mistake in the Melting/Boiling points part. The MP/BP increases from Na to Al not Na to Mg. My apologies
    A very very teensy mistake haha.
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    (Original post by NabRoh)
    Could someone explain to me how shells are filled up using Indium as an example?
    Does the 4th shell have an f block (14?)?

    So if we went up to the 6th shell would it be:

    1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 ...

    What comes next?
    5s2 4d10 5p1

    There aren't f blocks yet. At least thats what I think
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    (Original post by x-Sophie-x)
    5s2 4d10 5p1

    There aren't f blocks yet. At least thats what I think
    So the 4th Shell goes up to D orbitals? Do you know what the 5th one goes to?
    I saw the f-block thing when looking for answers on Wikipedia,
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    (Original post by NabRoh)
    Could someone explain to me how shells are filled up using Indium as an example?
    Does the 4th shell have an f block (14?)?

    So if we went up to the 6th shell would it be:

    1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 ...

    What comes next?
    4f doesn't come into play until after 6s
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    (Original post by NabRoh)
    Could someone explain to me how shells are filled up using Indium as an example?
    Does the 4th shell have an f block (14?)?

    So if we went up to the 6th shell would it be:

    1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 ...

    What comes next?
    Here's a picture illustrating the order in which electron subshells fill. Sorry for my bad paint skills xD
    Learn how to draw this diagram and you'll never forget the order of subshells.
    Attached Images
     
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    (Original post by Sharif Chowdhury)
    Here's a picture illustrating the order in which electron subshells fill. Sorry for my bad paint skills xD
    Learn how to draw this diagram and you'll never forget the order of subshells.
    Wow that is some confusing diagram.

    I remember the subshells by just looking at the periodic table and counting along..
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    (Original post by NabRoh)
    So the 4th Shell goes up to D orbitals? Do you know what the 5th one goes to?
    I saw the f-block thing when looking for answers on Wikipedia,
    Yep. If you look at a periodic table and count along, it will make things a lot clearer

    The 5th one has d orbitals as well. No F orbitals yet.
    We dont need to know about f orbitals in unit 1 chemistry
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    (Original post by x-Sophie-x)
    Wow that is some confusing diagram.

    I remember the subshells by just looking at the periodic table and counting along..
    Omg, I didn't even realise you could do that, I feel silly now... haha, you learn something new every day.
 
 
 
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