Lewis structure help :(

Have you not learnt how atoms bond to each other covalently and the way they share electrons? apply those basic rules here and it should work.

Important thing to look for is the number of valence electrons and then go on from there.

Yes i have but im not sure how to apply this to drawing lewis structures

So ive added all the valence electrons. I had to draw one extra for oxygen and one less for Xe so it would fit but obviously this is wrong. Where do i go from here?

You are missing out an important fact. How many electrons does each atom contribute? Take a look and you will realise something.

At the moment they are all contributing one electron???

Nope. Look at how many electrons Xe, F and O have in their outer energy level. Then see how they each contribute electrons.

Oh yeah oops

Xe - 8 outer electrons (contributes 5)
Fe - 7 outer electrons (contributing 1)
O - 6 outer electrons (contributing none???)

Fe? It's Fluorine so should be F? Also, when bonding, how many lone pairs does O have generally which it can contribute? F can contribute how many electrons to have a complete orbital? What do you think?

yeah sorry its F, idk whats wrong with me today

F needs 1 more electron for an octet and oxygen needs 2??

Okay. So there are a total of 42 valence electrons. 8 from Xe, 6 from O and 28 from F (7 from each F atom). You know that Xe will be the central atom. now figure out how it will bond with Oxygen so it has a full energy level. After you figure this out, Fluorine should be relatively simple.

Ok so i know its a double bond but how do you decide this? Is it because oxygen needs 2 electrons to form an octet?

Yes. Oxygen and Xe will have a double bond because that is the way Oxygen will achieve a double bond. Now, decide how other atoms will pair

Oh so its based on the number of electrons needed to achieve an octet?

So fluorine needs 1 electron - single bond
Oxygen needs 2 - double bond
Xenon - .... already has an octet?? Im confused

you are right that fluorine needs 1 electron to have a full octet but there are 4 F atoms so you will have 4 single bonds. Therefore, in total you have

one double bond + 4 single bonds = 4 + 8 electrons which means 12 valence electrons have been used and you are left with 30 valence electrons.

so 15 electron pairs? - add as valence electrons??

generally speaking for lewis structures do you draw the single bonds then add valence electrons. Then how do you decide if you need a multiple bond i.e. double/triple etc.??

Yes there are 15 electron pairs and you add them as lone pairs to each atom in your structure.

I personally don't see a big difference with questions of this type. You know O will have a double bond even if you don't work out the valence electrons. Although generally it is better to work out the valence electrons and then see what bonds are formed but saying that, doing it either way is fine because it doesn't make a big difference.

Ok thanks for your help

Would you be able to help me with this too??
https://www.thestudentroom.co.uk/showthread.php?t=5087614

Ok thanks for your help

Would you be able to help me with this too??
https://www.thestudentroom.co.uk/showthread.php?t=5087614

note, although the double bond to O is obviously a 4 electron bond, for the purposes of VSEPR it counts as one group, the same as a single bond.