Join TSR now and get all your revision questions answeredSign up now

Relative atomic mass mass spectra

    • Thread Starter
    Offline

    2
    ReputationRep:
    Name:  image.png
Views: 25
Size:  72.1 KB How do you work out the relative atomic mass? I don't have a clue... Someone please take me through step by step
    Offline

    2
    ReputationRep:
    2a. 2,8,8,8,8,8,8,2
    2b.
    i.I dont know
    ii. different isotopes
    you should get a revision guide.
    Offline

    3
    ReputationRep:
    (Original post by KnowledgeIsBest)
    2a. 2,8,8,8,8,8,8,2
    2b.
    i.I dont know
    ii. different isotopes
    you should get a revision guide.
    Presuming this is an A level paper your answer to 2a would get precisely zero marks out of one every single time.
    Offline

    2
    ReputationRep:
    (Original post by MexicanKeith)
    Presuming this is an A level paper your answer to 2a would get precisely zero marks out of one every single time.
    why? and its not an A-level paper, its a GCSE additional science question.
    Offline

    3
    ReputationRep:
    (Original post by Lucofthewoods)
    Name:  image.png
Views: 25
Size:  72.1 KB How do you work out the relative atomic mass? I don't have a clue... Someone please take me through step by step
    Relative atomic mass is simply the average of the isotopic masses, each weighted with the abundance of that isotope.

    For example Chlorine has two common isotopes
    35Cl (~75% abundance) and 37Cl (~25% abundance)
    (ie 3/4 of chlorine is 35, 1/4 of chlorine is 37

    so the relative atomic mass of chlorine would be

    (35 x 3/4) + (37 x 1/4) = 35.5

    Hopefully that example might give you an idea how to do this question
    Offline

    3
    ReputationRep:
    (Original post by KnowledgeIsBest)
    why? and its not an A-level paper, its a GCSE additional science question.
    Okay, GCSE additional science, that might be an acceptable answer (struggling to remember back that far!)

    The reason it wouldn't get the marks in my book is simply because the question asks for an electron configuration, and a series of numbers is not a configuration.

    A configuration would look more like this:

    1s22s22p63s23p64s23d104p65s24d105p4

    or more simply

    [Kr]5s24d105p4

    Which will make no sense to most GCSE students.

    If the examines were looking for the style of answer you gave then I think this is a rather unfortunate situation where GCSE oversimplifies. Sorry for jumping on your back about your answer!
    Offline

    3
    ReputationRep:
    (Original post by KnowledgeIsBest)
    why? and its not an A-level paper, its a GCSE additional science question.
    Just found the paper http://filestore.aqa.org.uk/subjects...1-QP-JUN15.PDF

    It's A level so your answer is definitely not going to get any marks

    also in the question it gives you [Kr] to begin with so it definitely wants the full configuration as I've given above!
 
 
 
Poll
Do you have exam superstitions?

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.