vedmecum

Can anyone tell me what T2g means. T is triply degenerate and g is "even" so what is 2?

 

Also, what do the numbers in A1 and B1 and B2 mean.

 

Also what do the letter stand for? If T is for triply degenerate then what does E for if it means doubly degenerate as doubly clearly doesn't start with e.

---

Merged post follows:

Consecutive posts merged

One more thing can someone give a good reference for generating character tables. The math behind it and all that good stuff.

here is one correction in your first line- g is used when the complex is octahedral and it has no relation with even or odd figure.... try a book group theory by sutton ..

hi guys .... i want some very useful information from that weblink from which old content was removed and new data is uploaded ......... is there any way to get that old data????? i will be highly thankful to all those who guys who will help me :-):-) ...........

hello......if anybody how molecule rotate plane of polarised light then please let me know also ........ upto my knowledge there are certain kind of vibrations in a molecule which cancel the vibrations of light in all direction leaving one ........ but i wanna know how these vibrations get cancel out.???? i need any sort of hint or ans. (which is banned in this forum).......

thanks for your concern .........

you said that we can calculate optical rotation of single molecule but its a very hard job ....... can you please suggest me any method 4 finding optical rotation of single molecule ????

good evening ......

yesterday when i was i reading a book of stereochemistry by Eliel few ques. ( may be foolish ) came to my mind ......... is their any relation between degree of optical rotation of a molecule and its various unstable conformations ( not configuration) ?????........how can we say that these particular molecule rotate plane polarized light to any specific degrees ?????

we normally calculate optical rotation of a solution i.e a collection of molecules ...... why don't we look for optical rotation of a single molecule ?????? if the degree of optical rotation is related with conformations of molecule then there may be possibility that in a single solution we have different species which can have different optical rotation ........

is there any mathematical equation which can relate degree of optical rotation with dihedral angle of molecule ?????

May be this will help you .......... look for the both thermodynamically and kinetically derived product ........... in A there is a formation of allylic intermediate which is more stable than primary carbocation as in case of B .......... so A intermediate will form at a faster rate than carbocation ........ results in formation of 1,2 addition product in major amount ...........so 1,2 product is kinetically favored ........ now look on the final product ......... 1,4 product is more stable than 1,2 as 1,4 product is more substituted alkene so thermodynamically favored ......... so as soon as 1,2 product form there is enough collision energy ( even at room temp. ) to pass over the energy barrier from 1,2 product to 1,4 product........

hi to all . i need urgent help . i am using windows vista sp1 and windows 7 on a same pc . windows 7 is running awesome but there came problem in windows vista . i was playing a game and suddenly screen rotates by 90 degree . may be there is some problem in windows or in monitor driver . may be its in vista because windows 7 is running fine . try to resolve this problem .

thank you ....

hi all,

 

just a couple of points I want clarification on;

 

1. Orbitals in many-electron atoms are lower in energy than the hydrogenic orbital.

 

I dont understand this bit. when the principal quantum number increases, the radial function increases, so the energy should infact increases due to increased screening effect. But this statement says the opposite!

 

2. d orbitals are poorly shielded so that nd orbital is of slightly higher energy than (n+1)s orbital for a gasesous element. e.g. ...4s<3d...!

 

I dont get it, when d orbitals are poorly shielded they should be penetrating the core much better than (n+1)s orbital and experience the Zeff more and thus should be lower in energy.

 

can anyone explain these two points please or maybe direct me someplace where I can find the answer.

 

thnx

up to my knowledge there must be a correction in your statement . d-orbitals are not poorly shielded but they shield poorly . This result in slightly decrease in energy of outer orbitals electron .

for energy comparison http://www.chemguide.co.uk/atoms/properties/atomorbs.html

i don't think that its -O-S(O)Cl- is the leaving group in case of SOCl2 and same for PCl5 , have a look on mech.

http://www.cem.msu.edu/~reusch/VirtualText/Images2/alcolrx1.gif

hi jerryshizzle123 , you said that u end up with MnO2 , these may be because of reaction condition which you had taken .

Potassium permanganate is manufactured on a large scale from manganese dioxide, which is fused with potassium hydroxide and heated in air or with potassium nitrate (a source of oxygen). This leads to the formation of potassium manganate, which on electrolytic oxidation in alkaline solution gives potassium permanganate.

MnO2 + 2OH− + O2 → MnO42− + H2O

so instead of taking acidic medium try basic medium so in case MnO2 form , it will further electrolyzed to KMnO4 .

The carbon atom of a carboxyl group is in a relatively high oxidation state. Reduction to a 1º-alcohol takes place rapidly on treatment with the powerful metal hydride reagent, lithium aluminum hydride, as shown by the following equation. One third of the hydride is lost as hydrogen gas, and the initial product consists of metal salts which must be hydrolyzed to generate the alcohol. These reductions take place by the addition of hydride to the carbonyl carbon, in the same manner for aldehydes and ketones. The resulting salt of a carbonyl hydrate then breaks down to an aldehyde that undergoes further reduction.

4 RCO2H + 3 LiAlH4 ether__>

4 H2 + 4 RCH2OM + metal oxides H20__>

4 RCH2OH + metal hydroxides.

Addition of a hydride anion to an aldehyde or ketone would produce an alkoxide anion, which on protonation should yield the corresponding alcohol. Aldehydes would give 1º-alcohols (as shown) and ketones would give 2º-alcohols.

RCH=O + H:(–) RCH2O(–) + H3O(–) RCH2OH

practical source of hydride-like reactivity are the complex metal hydrides lithium aluminum hydride (LiAlH4).

so LiAlH4 reduces all aldehydes and ketones .

:-)why you wanna do this by electrolysis as these is both time consuming and require precision too . add those reagents which can form insoluble complexes with calcium and magnesium .

:-)acetone by itself is an excellent solvent . i am not providing you complete ans , just a hint for you :- polar solute dissolve in polar solvent and non polar solute in non polar solvent . or ionic substances are soluble in ionic solvents and same for covalent .

Tartaglia ,may be your ans. is correct to some extent but mine guess was also correct , you can verify it from the following links:-

1. http://www.chemguide.co.uk/inorganic/complexions/ligandexch.html

2. http://www.britannica.com/EBchecked/topic/136410/coordination-compound/277812/Substitution#ref=ref1008332

3. pages 706-710 http://books.google.com/books?id=ocKWuxOur-kC&pg=PA701&lpg=PA701&dq=substition+reaction+in+inorganic+chemistry&source=bl&ots=M7v4IiixEZ&sig=BaCbUwt8vT5_f6C5JEwlTC-PG7o&hl=en&ei=5t_mSbTWLsuHkQXy6pWbBw&sa=X&oi=book_result&ct=result&resnum=9#PPA711,M1 . :-)

i don't know correct ans . but acc. to me its n't because of NO but due to formation of pentavalent ( sp3d hybridization ) transition state (as in your case) which acc. to Werner theory is highly unstable so complex again get its tetravalent state .

definitely because of vacant d-orbital . let me provide you 2 hint

1 . there is a difference between hydration and hydrolysis .

2 . there is a formation of pentavalent transition state in sn2 type reaction but due to small size of carbon atom and limit of using only s and p orbital it again goes to tetravalent state . :-)

Let's take an odd example, but one where the chemistry is relatively simple.

Potassium has a naturally ocurring isotope of mass 40 which decays (mainly- but lets ignore the other possibility for a minute) by beta decay to give argon. It has a half life of 1.25 billion years I think)

 

Imagine that we extract some of this isotope of potassium and turn it into the chloride.

 

It decays slowly but surely to argon, and of course, argon doesn't form a chloride.

 

So the reaction is

2 KCl --> 2Ar +Cl2.

The potassium was there as K+ ions and when they lost a beta particle they (briefly) became Ar++ ions.

Now Ar(II) is a much stronger oxidant that you get in any normal sort of chemistry. It's perfectly capable of oxidising chloride to chlorine.

 

In case you are wondering, the beta particle will hit something and stop. Then it's just an electron. Now tha electron (on it's own) is a very powerful reducing agent. It can certainly reduce Ar+ to Ar

okay this unravel 1st situation and what about second because to balance UC reaction we need almost double amount of Cl- , upto my knowledge CaCl+ is less stable than CaCl2 .

Merged post follows:

Actually, beta decay would convert potassium into calcium...

 

[ce] KCl -> CaCl^+ + e^- [/ce]

both u and john are correct . you are talking about beta- decay and john has given an example of beta+ decay .

:-) finally we reach at that point where i think we need to discuss more of chemistry as mine first ques. still not completely unravel . from the above posts what i concluded is that reaction will take place but the major ques. which struck in my hypothalamus is how reaction will balance by itself ? because if , for ex , we take uranium oxide in which uranium is in x+ oxidation state and we end with oxide of different element in +y oxidation state then how stiochiometry will be maintained . there will be 2 or more situation possible:-

1. new comp. have lesser no. of oxygen , then where the remaining oxygen will go ? . will we get free oxygen (if we took uranium oxide) ? if so then isn't amazing ?

2. if new comp. have higher no. of oxygen then from where it comes ?

Right.

 

After the decay you might expect the U to have 2 extra electrons, but it's more likely that the decay ionizes several electrons. When I was trapping radioactive K, studying the effects of decay, we found that the beta-plus decay of K-37 would only rarely leave you with Ar^- or Ar⁰. More often you'd end up with Arⁿ⁺, with n = 1, 2 or 3. i.e. very often the decay would strip off several electrons. This is only from a beta, i.e. a single charge and little nuclear recoil.

 

So after a U decay in an oxide, I don't think you can assume you have a molecule anymore.

i agree with you as per K-37 (that we get noble element in last ) is concerned but i think we can't apply it universally for all radioactive substance . for example log on

http://wiki.answers.com/Q/What_is_the_decay_products_of_uranium_238 and http://www.atral.com/U2381.html and there are many more links which indicates that the end product will be lead-206 . so now why not oxide of lead -206 form or it may form ?

 

EDIT: And I start to begin to understand why we did understand the OP differently. I think vedmecum did indeed ask what happens to the chemical binding, not whether the binding will influence the decay of the Uranium nucleus.

sorry because two of you have taken my ques. in a different sense but my exact ques. is what is written above . this is first time when i have no idea .

Merged post follows:

it was a shock. i have never thought that. what happens to electrons in the shell of uranium after decay? i believe they must stay there but now the atom should be negatively charge? outer electrons will be less strongly bound?i cant undertstand it either. if we take elemental uranium and it decays then will the extra electrons just fly away in space? if not wont we have -ve charged particles repelling each other strongly?

no amit . log on http://en.wikipedia.org/wiki/Nuclear_decay

may be i am asking the foolish ques. but these ques. is really disturbing my hypothalamus .

we are all familiar with nuclear reaction . the most familiar one is the one with uranium . it changes to thorium, radon , polonium , radium or.......... depending upon the type of decay either its alpha, beta or any other .

now if we take not elemental uranium but its oxide which is widespread then how stiochiometry will be maintained i.e there may be formation of oxides of thorium, radon , polonium , radium or.......... , but from where oxygen comes ????????????:confused::confused::confused::confused::confused::confused::confused::confused::confused:

you are creating confusion in between two terms :- solvolysis and reaction as they differ a bit .

and if i am not wrong then the competing reaction is elimination reaction just because of tertiary carbon .

i have one problem which is blundering my CNS . when an alkyl halide is added to alc.KOH , there is an alkene formation. Alcohol is there but no ether formation takes place . how ? why ?

What is ABS ?

sodium and potassium are not present in elemental form . both are present in ionic form in body . for complete chemistry of these ions click on http://charles_w.tripod.com/arthritis4.html.