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

    10
    ReputationRep:
    A chemistry question asks which of the following has three lone pairs of electrons around the central atom and the possible multiple choice answers include BF2 -
    (2 flourines and a negative charge) and CIF2 - ? I thought only a metal and non metal could form an ionic bond? do I not know this because I've just started year 12 and I haven't learnt of this yet?
    Offline

    12
    ReputationRep:
    It’s not ionic bonding that the question is about, the answer is ClF2 - because the Cl is in group 7 so naturally has 7 outer electrons, when bonded to two other atoms it would have 2 lone pairs and a free radical (don’t worry if you haven’t learnt this yet because you will) adding another electron causes the free radical to just become another line pair whilst giving an overall charge or -1 because of the extra electron
    Posted on the TSR App. Download from Apple or Google Play
    Offline

    12
    ReputationRep:
    ClF2- will have 3 lone pairs of electrons around the central atom (Cl). This is because chlorine has 7 valence electrons (it's in group 7), and flourine has 7 valence electrons, and there's two of them. There's also a negative charge, meaning there's one extra electron.

    Add the number of electrons up, you get 22 electrons. A full outer shell will have 8 electrons, so if you take away the highest multiple of 8 under the number of electrons (22), you get 16. 22-16=6. So there are 6 electrons unpaired around the central atom, but they exist in pairs, so 6/2=3. There are 3 lone pairs.

    If you draw the dot and cross structure of ClF2- you will see this shown more clearly. Also, these compounds do not have ionic bonding, they show covalent bonding, they share electron pairs.
    Posted on the TSR App. Download from Apple or Google Play
 
 
 
  • 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.

  • Did TEF Bronze Award affect your UCAS choices?
    Help with your A-levels

    All the essentials

    The adventure begins mug

    Student life: what to expect

    What it's really like going to uni

    Rosette

    Essay expert

    Learn to write like a pro with our ultimate essay guide.

    Uni match

    Uni match

    Our tool will help you find the perfect course for you

    Study planner

    Create a study plan

    Get your head around what you need to do and when with the study planner tool.

    Study planner

    Resources by subject

    Everything from mind maps to class notes.

    Hands typing

    Degrees without fees

    Discover more about degree-level apprenticeships.

    A student doing homework

    Study tips from A* students

    Students who got top grades in their A-levels share their secrets

    Study help links and info

    Can you help? Study help unanswered threadsRules and posting guidelines

    Sponsored content:

    HEAR

    HEAR

    Find out how a Higher Education Achievement Report can help you prove your achievements.

    Groups associated with this forum:

    View associated groups
  • 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.