Question

how come Sulfur have more than 8 electrons in its valence ? i dont seem to understand these structures having more than 8 valence electrons, coiuld somebody plz explain plzzz

Answer 1

http://upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Sulfuric-acid-2D-dimensions.svg/228px-Sulfuric-acid-2D-dimensions.svg.png

Answer 2

sulfur's valence level (3p) is very close to the 3d level above it. Sulfur can use these nearby orbitals to make more than 4 bonds, which smaller atoms can't do. Phosphorus can do this also, but no atoms smaller than phosphorus can "expand" their octet like this

Answer 3

what does that mean... looks like a new concept :(
i learned only that all elements try to get 8 electrons in valence.

since S & O both have 6 electrons in valence, they need 2 more electrons for octet, so it can have 2 lone pair of electrons + 2 double bonds with O, S=O

Answer 4

let me read ur reply again. .

Answer 5

u mean, both 3p and 3d can work as valence for S ? both 3p and 3d energy levels are nearby eachother ?

Answer 6

yes, both levels can be used as valence levels for sulfur. Oxygen doesn't have a "2d" level above its 2p valence level, so oxygen can't expand, but sulfur can

Answer 7

oh my teacher didnt talk about this yet, so all elements in the same period of S, can do this ?

Answer 8

Cl, Si, P are also in the same period

Answer 9

no, only nonmetal elements phosphorus and larger: P, S, Cl, As, Se, Br, etc etc

Answer 10

oh it works with 4p 4d also seems i get it !

Answer 11

and ideal gases are not affected by this ? they're stable as usual is it

Answer 12

the (PO4)-3 ion looks the same kind of way, with more than 4 bonds. the (BrO4)-1 ion looks the same kind of way

Answer 13

oh ya, SO4-2 also looks similar more than 8 electrons

Answer 14

so whats the stable configuration for these, S, Br.. .

Answer 15

i mean, like octet rule, how many electrons in valence for S would make it stable ?

Answer 16

18 ?

Answer 17

the octet rule means 8 electrons "usually" will make an atom stable, but in the case of sulfur, it can support up to 6 bonds, so that's 12 electrons total. If we have to make a structure using sulfur, we usually try to make the octet rule fit, but we can break it if we have to. When teaching the octet rule, I usually like to leave sulfur with an octet, like in SO2, or H2S, rather than using it in bigger ions like (SO4)-2

Answer 18

oh i get octet rule for other elements, but as u say S looks to be stable both as octet and when it has 12 electrons in valence.. . or did i get u wrongly ? i may aswell wait till our teacher introduces these... but since u r there... i just wanto knw this fully now

Answer 19

sulfur can be happy with either, so you do have it mostly correct

Answer 20

thank you :)

Answer 21

The octet rule is only a tendency, not in any sense a rigid rule that is always true. There are many exceptions to it -- in fact, the compounds made from *most* of the elements in the Periodic Table violate the octet rule. Only organic compounds (made of carbon, hydrogen, oxygen, nitrogen mostly) routinely follow the octet rule.

In general, it can be considered pretty reliable in Periods 1 and 2, except for Be and B. For Period 3 nonmetals, it's obeyed by a lot of compounds, but by no means all. It's not really followed at all by transition metals, or by elements in Period 4 and higher.

As for what really determines the number of electrons around an atom, one can often get a good impression from the approach @jFraser advocates, which is too look closely at the orbitals available at around the same energy, the energy of the valence electrons. As you go higher and higher in the PT, you have more and more and more closely-spaced (in energy) orbitals, so not surprisingly you start to be able to accomodate more and more electrons around each atom. Trying to figure out the exact number, however, can be challenging, because of the subtle changes that happen in energy when orbitals get involved in bonding. That's why we can't give a simple answer to the question: "How many electrons does every atom want around it?" We say "eight" when we first start teaching chemistry, because it's something to start with. But sooner or later we have to admit the answer is way more complicated, and there are often no simple answers. Except, as I said, in pure organic compounds, where the octet rule is a very good guide in general.