Hey there! Sign in to join this conversationNew here? Join for free
Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    basically chem q:

    explain why the 2nd ionisation energy of sodium is greater than the second ionisation energy of magnesium?

    My answer-
    na+ has full outer shell (noble gas E.c) stable, so doesnt want lose/gain electrons- difficult to ionize, whereas mg+ will readily lose another electron-to gain full outer shell, so more energy needed to ionize sodium

    Checked on internet-
    someone wrote this-


    Once sodium loses one electron it satisfies the octet rule because it now has 8 electrons in it's outermost shell. So it is stable. More stable than if it lost another electron (which would result in it having only 7 in the outermost shell). So you require more energy to pull out that second electron.

    Magnesium on the other hand, needs to lose 2 electrons to satisfy the octet rule. So pulling out the second electron will be easy (coz it would rather be in a state with 8 electrons in the outermost shell). Hence .. second ionisation energy (energy required to lose the second electron) is greater in sodium than in magnesium


    But mark scheme?!:
    doesnt give any marks for above^!!!

    Question- are ions with noble gas configs stable? why wont mark scheme let this?
    Offline

    15
    ReputationRep:
    It is simply that the second electron to be removed in the Na ion is in the 2p orbital where as for magnesium the second electron is in the 3s orbital.

    Electrons closer to the nucleus are held more tightly, less electron shielding and a greater charge ratio with the nucleus.
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Mockery)
    It is simply that the second electron to be removed in the Na ion is in the 2p orbital where as for magnesium the second electron is in the 3s orbital.

    Electrons closer to the nucleus are held more tightly, less electron shielding and a greater charge ratio with the nucleus.
    D: thanks! but how do i know im sposed to write that!!!
    Offline

    14
    ReputationRep:
    In Na+, the outer electron is closer to the nucleus because it has one less shell, there is more nuclear attraction making it difficult to remove electron. Mg is easy to remove as there are more shells between outer electron and nucleus so there is more of the shielding effect, so the nuclear attraction is weaker so less energy needed


    Revising my socks off for unit 1!
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by letsbehonest)
    In Na+, the outer electron is closer to the nucleus because it has one less shell, there is more nuclear attraction making it difficult to remove electron. Mg is easy to remove as there are more shells between outer electron and nucleus so there is more of the shielding effect, so the nuclear attraction is weaker making it easy to remove electron.


    Revising my socks off for unit 1!
    thanks ! im revising for unit 1 too but im so dead cuz eevryone makes everything seem simple but when i do exam i get blank mind ):
    Offline

    14
    ReputationRep:
    (Original post by Yep)
    thanks ! im revising for unit 1 too but im so dead cuz eevryone makes everything seem simple but when i do exam i get blank mind ):
    Are you doing OCR A?
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by letsbehonest)
    Are you doing OCR A?
    nope, aqa D:
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: January 1, 2013
Poll
“Yanny” or “Laurel”

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

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