Hey there! Sign in to join this conversationNew here? Join for free
    Offline

    0
    ReputationRep:
    (Original post by yodawg321)
    Just scroll underneath the questions. The mark scheme is there
    Oh right , thank you
    Offline

    2
    ReputationRep:
    (Original post by yodawg321)
    Question

    Explain the decrease in atomic radius across each period?
    Predict and explain whether a sodium ion is larger or smaller than a sodium atom.
    Why does the boiling point increase from Sodium to Aluminium?
    Atomic Radius Decrease...
    ->Electrons added to same shell, no extra electron shielding
    ->Greater nuclear charge, with increase of protons and electrons
    ->Greater nuclear attraction between nucleus and outer shell electrons, pulling them closer... thus decreasing the atomic radius.

    Na ion compared with Na atom
    -> larger, referring to atomic radius.
    -> Na atom has 11 electrons, 1 electron in outer shell.
    -> Na+ has 10 electron, 8 in outer shell
    -> Na+ has less electron shielding.
    -> Na+ will have greater nuclear attraction for outer shell electrons.
    -> Same nuclear charge.
    -> Thus Na+ will have smaller atomic radius, so Na atom is larger.

    Na -> Al
    -> Across same period, both form strong metallic bonds.
    -> Decrease in atomic radius across period, Al has smaller radius
    -> No difference in electron shielding, electrons added to same shell
    -> Al has greater nuclear charge, due to addition of protons and electrons
    -> Al had greater nuclear attraction for it's outer shell electrons
    -> thus more energy is required to break Al metallic bonds.


    Please correct if I've gone wrong somewhere, but this is my thought process to answering those type of questions

    EDIT: Good point from above for Na -> Al, greater nuclear attraction means greater electrostatic attraction between delocalised electrons and positive Al3+ ions within metallic lattice.
    Offline

    2
    ReputationRep:
    Do we have to know about the history of the 'model of an atom'?
    Offline

    0
    ReputationRep:
    what do u guys think might come up in tomorrows exam?
    Offline

    0
    ReputationRep:
    Two questions;
    Can someone please explain how bond angles of 104.5 are made?
    Also, in the Jan 2013 paper on the ionisation energy question 3c, why is there a big jump between the 6 and 7th?
    Thanks
    Offline

    0
    ReputationRep:
    (Original post by Liberty.)
    Atomic Radius Decrease...
    ->Electrons added to same shell, no extra electron shielding
    ->Greater nuclear charge, with increase of protons and electrons
    ->Greater nuclear attraction between nucleus and outer shell electrons, pulling them closer... thus decreasing the atomic radius.

    Na ion compared with Na atom
    -> larger, referring to atomic radius.
    -> Na atom has 11 electrons, 1 electron in outer shell.
    -> Na+ has 10 electron, 8 in outer shell
    -> Na+ has less electron shielding.
    -> Na+ will have greater nuclear attraction for outer shell electrons.
    -> Same nuclear charge.
    -> Thus Na+ will have smaller atomic radius, so Na atom is larger.


    Na -> Al
    -> Across same period, both form strong metallic bonds.
    -> Decrease in atomic radius across period, Al has smaller radius
    -> No difference in electron shielding, electrons added to same shell
    -> Al has greater nuclear charge, due to addition of protons and electrons
    -> Al had greater nuclear attraction for it's outer shell electrons
    -> thus more energy is required to break Al metallic bonds.


    Please correct if I've gone wrong somewhere, but this is my thought process to answering those type of questions

    EDIT: Good point from above for Na -> Al, greater nuclear attraction means greater electrostatic attraction between delocalised electrons and positive Al3+ ions within metallic lattice.

    Sodium Ion will be smaller because it will turn into a +1 ion.
    This will result in smaller shells than Na atom.
    So there will be more nuclear attraction as the remaining electrons will be attracted to the nucleus more.

    and for the Na-Al bit you basically got that right.

    All you have to say is that

    Al has more delocalised electrons.
    Al has more ionic charge
    So there is a greater nuclear attraction
    More energy needed to break the strong metallic bonds.
    Offline

    0
    ReputationRep:
    (Original post by HelenPaddock)
    Two questions;
    Can someone please explain how bond angles of 104.5 are made?
    Also, in the Jan 2013 paper on the ionisation energy question 3c, why is there a big jump between the 6 and 7th?
    Thanks
    So the first bond angle is 120, thank you know that.

    The second bond angle is 104.5 because you have to look at the central atom.
    You can see that it has 2 bonded pairs and 2 Lone pairs
    2 Lone pairs will make the shape Non-Linear aka 104.5 degrees.
    Offline

    2
    ReputationRep:
    (Original post by HelenPaddock)
    Two questions;
    Can someone please explain how bond angles of 104.5 are made?
    Also, in the Jan 2013 paper on the ionisation energy question 3c, why is there a big jump between the 6 and 7th?
    Thanks
    Okay, oxygen has 8 electrons. 2 in it's 1st shell, and 6 in its 2nd shell. The 6th ionisation energy you are still removing electrons from the 2nd shell. But when you reach the 7th, you've already taken all of the 6 electrons in the 2nd shell, so you start removing electrons from the 1st shell. Since the 1st shell is closer to the nucleus it experiences more electrostatic attraction, and less electron shielding since it's the first shell.
    Offline

    2
    ReputationRep:
    (Original post by Liberty.)
    Do we have to know about the history of the 'model of an atom'?
    No I don't think so, it isn't on the specification.
    Offline

    0
    ReputationRep:
    Ahh makes sense, thank you
    Offline

    0
    ReputationRep:
    (Original post by sladyy96)
    can someone please explain hydrogen bonding?
    Hydrogen Bonding:
    Basically another type of intermolecular force that can only occurs between:
    -δ+ Hydrogen atom on one molecule
    -and the lone pair of electrons on the δ- atom of the neighbouring molecule

    As long as you can draw it you'll be fine... For example with water draw two molecules of H20 and make sure you put on the δ charges and then draw a dotted line from the δ+ H on one to the lone pair of electrons on the O atom on the other molecule!
    Offline

    0
    ReputationRep:
    (Original post by joshturnbull123)
    Hydrogen Bonding:
    Basically another type of intermolecular force that can only occurs between:
    -δ+ Hydrogen atom on one molecule
    -and the lone pair of electrons on the δ- atom of the neighbouring molecule

    As long as you can draw it you'll be fine... For example with water draw two molecules of H20 and make sure you put on the δ charges and then draw a dotted line from the δ+ H on one to the lone pair of electrons on the O atom on the other molecule!
    great, thank you!!
    Offline

    3
    ReputationRep:
    (Original post by sladyy96)
    can someone please explain hydrogen bonding?
    Sure. A strong dipole-dipole attraction between an electron defecient hydrogen atom on one molecule and a lone pair of electrons on a highly electronegative atom on another molecule
    Offline

    0
    ReputationRep:
    (Original post by HelenPaddock)
    Two questions;
    Can someone please explain how bond angles of 104.5 are made?
    Also, in the Jan 2013 paper on the ionisation energy question 3c, why is there a big jump between the 6 and 7th?
    Thanks
    Not sure if this answers your question directly, but the way I look at it is according to the number of regions of electron densities...
    6 regions: 6bonds(octahedral)
    4 regions: 4bonds(tetrahedral); 3bonds and 1lonepair(pyramidal); 2bonds and 2lonepairs(non-linear)
    3 regions: 3bonds (trigonal planar); 2bonds and 1lonepair (non-linear)
    2 regions: 2bonds (linear)

    if you just remember the angles for octahedral, tetrahedral, trigonal planar, and linear, you can work out the others. Everytime there's a lone pair instead of a bond, the angle decreases by 2.5deg.
    For example, for the shapes with 4 electron density regions:
    4 bonds is 109.5deg; 3bonds and 1lonepair is 107deg; 2bonds and 2lonepairs is 104.5deg.
    Offline

    3
    ReputationRep:
    How are Van Der Waals formed?
    Offline

    0
    ReputationRep:
    Which shapes are symmetrical and which are asymmetrical? Can't picture them in my head
    Offline

    3
    ReputationRep:
    (Original post by sladyy96)
    Not sure if this answers your question directly, but the way I look at it is according to the number of regions of electron densities...
    6 regions: 6bonds(octahedral)
    4 regions: 4bonds(tetrahedral); 3bonds and 1lonepair(pyramidal); 2bonds and 2lonepairs(non-linear)
    3 regions: 3bonds (trigonal planar); 2bonds and 1lonepair (non-linear)
    2 regions: 2bonds (linear)

    if you just remember the angles for octahedral, tetrahedral, trigonal planar, and linear, you can work out the others. Everytime there's a lone pair instead of a bond, the angle decreases by 2.5deg.
    For example, for the shapes with 4 electron density regions:
    4 bonds is 109.5deg; 3bonds and 1lonepair is 107deg; 2bonds and 2lonepairs is 104.5deg.
    Do we have to know the 5 bonding regions. Triagnol Bipyramid. There are two angles for it.. 90deg at equator and axis, 120deg at equator
    Offline

    0
    ReputationRep:
    (Original post by Freddy-Francis)
    Do we have to know the 5 bonding regions. Triagnol Bipyramid. There are two angles for it.. 90deg at equator and axis, 120deg at equator
    No we don't need to know that
    Offline

    3
    ReputationRep:
    (Original post by megan1096)
    Which shapes are symmetrical and which are asymmetrical? Can't picture them in my head
    Symmetrical - Dipoles cancel out each other. The molecules are Non-Polar.
    asymmetrical - Dipoles dont cancel out but adds together to make a molecule with a larger dipole moment.
    Offline

    3
    ReputationRep:
    (Original post by yodawg321)
    No we don't need to know that
    ok. I take ur word
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Brussels sprouts
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.