Help Needed for the following questions

[ChemSiddiqui]

Hi, I have a few questions which I need u ppl to answer.

 

1. Its so confusing sometimes when you read books about which orbital is filled first 3d or 4s in d-block elements. I think since 4s has lesser energy so it is filled first. Is it correct or it is only a rule when writing electronic cofiguration?

 

2. I have come across with 'Group IIIA' or 'IVB" what does A and B mean here?

 

3. This one came in one the other forums I recently joined and there was this questions. I am going to present my answer to you but I need help. So here it goes:

 

"Given that on mole of particles is exactly 6.02 x 10^23 particles, deduce:

 

(a)the number of electrons required to convert 3.21g of sulphur into sulphide ions"

 

Now my take on it that: we will first of all divide 3.21 with 32 to get the number of moles of sulphur. we will then multiply the answer with the avogadro number to get the number of electrons required. What to do next????????????? or is it the answer.

 

Any help is most appreciated

[Testo]

1. Well its a bit fuzzy actually, your right in saying 4s is lower in energy but there are several exceptions to when the 3d is filled preferentially, most notably a half filled d-subshell has an element of stability (see hunds rules) so u get 4s13d5 instead of 4s23d4 etc.

 

2. It's just an old system of naming the groups, groups 1-18 are used now for clarity

 

3. Assuming u want the S- ion then yeah thats your answer.

[ChemSiddiqui]

Thnx 4 that but from your answer of '3' say the ion is S-2, then should we divide the answer by 2, is it?

[Testo]

Multiply by two

[YT2095]

groups 1-18 are used now for clarity

 

this at Best Wildly inaccurate! and I`v told you about this before and Why it is wrong.

let me try again...

 

look at group 4 (or 14 as you would call it).

there are 6 elements in that group; C, Si, Ge, Sn, Pb and Uuq.

 

your 14 method is only true for 2 of those 6 elements, namely Ge and Sn.

 

to use your way with any semblance of truth it would be

 

C= 4

Si= 4

Ge= 14

Sn= 14

 

and here comes the Fun bit...

 

Pb= 28

Uuq= 28

 

yes, you have to count the F block 14 too!

 

 

so Now can you see Why this "method" is totally Out-of-Order?

[Testo]

this at Best Wildly inaccurate! and I`v told you about this before and Why it is wrong.

let me try again...

 

look at group 4 (or 14 as you would call it).

there are 6 elements in that group; C, Si, Ge, Sn, Pb and Uuq.

 

your 14 method is only true for 2 of those 6 elements, namely Ge and Sn.

 

to use your way with any semblance of truth it would be

 

C= 4

Si= 4

Ge= 14

Sn= 14

 

and here comes the Fun bit...

 

Pb= 28

Uuq= 28

 

yes, you have to count the F block 14 too!

 

 

so Now can you see Why this "method" is totally Out-of-Order?

 

You seem to be under the impression that I have invented this system, i have not! And i'm very capable of counting electrons thank you, i think you need to get over the fact that this is nomenclature not 'how many outer electrons does the elements in the group have'.

 

i agree that it is a silly numbering system but there it is. In fact here is somebody whining about it;

 

http://homepages.paradise.net.nz/totomark/PeriodicTable/MarksBrosPT1994.html