Edexcel CHEMISTRY DOUBTS!!!!

[**RoRo**]

I have a question, do we need to know the shapes of the d orbitals? If yes, can someone please show me a clear diagram of them if we need to know them?

Thanks in advance!

[Amelia]

Yes, you do need to know them. d-orbitals are double dum-bell in shape. Look at the image below, you'll understand.
or just click on da link for a bigger image.


http://www.tutornext.com/system/files/u73/Chapter%203-final-10.gif

[The Golden Girl =D]

9)a) Ionization Energies decreases down the group, the greater the atomic number - size of the atom increases resulting in less nuclear pull.
     So, the answer is A.
   c) Noble gases have filled shells, which is the most stable configuration for an atom. Removing an electron from a noble gas would increase the energy more than if you removed an electron from, for example, nitrogen.
Answer is D (though I'm not sure about this one. )

not it's A .

[The Golden Girl =D]

11a) it's D.
 Addition reaction of C₄H₁₀
b) Ans is C - presence of Double bonds.


Thanks, Mr. Holmes.

Hmm 11]a is A By the way , and c) is C

I don't get them AT ALL T_T

[The Golden Girl =D]

Anyone ?

[Amii]

not it's A .

gg check again 
9c is D

[The Golden Girl =D]

gg check again  
9c is D

 i don't get 9]c) and a)  + 11] as well

I need this for tmrrw so plz help

[The Golden Girl =D]

(NH₄)₂SO₄ -----> 2NH₄⁺ + SO₄^2-

0.475/132 = 3.598 *10^-3 moles of Ammonium Sulphate

2*[3.598 *10^-3] = 7.197*10^-3 NH₄⁺ ions

Since concentration = no. of moles / volume

c = 7.197*10^-3 / 2 = 3.598*10^-3 moldm^-3

Converting moldm^-3 to gdm^-3 gives : 0.475 gdm-3

Converting gdm-3 to milligrams per dm3

we get 475 mgdm-3 or 475 ppm

Is this correct ?


It is important to note that 1 ppm = 1 milligram per decimeter cube.

how did you do this Ari ?   

[**RoRo**]

Yes, you do need to know them. d-orbitals are double dum-bell in shape. Look at the image below, you'll understand.
or just click on da link for a bigger image.


http://www.tutornext.com/system/files/u73/Chapter%203-final-10.gif

Thanks Hamlet!

[Amii]

okay 9 c

More energy is required to remove the 2nd electron than to remove the 1st electron.
This is because the 2nd electron is being removed from a postive ion,which is smaller than the original atom and experiences greater force of attraction.
Even more energy would be required toremove the 3rd electron and so on.

Hence the IE5>IE4>IE3>IE2>IE1 - should increase

so ofcourse not A or C.

Then if you look at B there is a big jump between the 1st IE and 2nd IE ---->which shows the second electron is being removed from the another inner shell.

But nobles gases have 8 electrons in the outer most shell - which means all the 5 electrons will be removed from the same shell - hence there should no jump in the values between the first 5 IE .

Therefore D - IE increases and no jump in the IE values

This is what I think  

I am sorry if it's confusing  

[Amii]

9a)In order of increasing atomic number----->means down a group
Down a group
The no. of shells increases that is more shielding effect.The electrons of the inner shells screen the attraction between the nucleus and the outer shell electrons.Hence it is easier to remove the electron.
Hence IE decreases down the group

Answer----> A

[Amii]

11 a ) gg I am seriously not sure of this - the explanation looks illogical to me but can't think of any other reason  
anyway  
the question says which compound is formed from one of the others in an addiction reaction.

Since it is an addition reaction the compund will be formed from a compund containing a double bond which is B.

The double bond is between the 2nd and 3rd carbon - when the pie bond breaks, the 2 new sigma bonds should be formed on the 2nd and 3rd carbon atom.

Not D---->The bromine atoms are attached to the 1st and 2nd carbon atoms.

Not B----> only 1 new sigma bond formed - and the chain is branched - no proper explanation for why not B but it is obvious right that the ans is not B

answer---->A
   H              H                             H H H H
H-C- C = C - C -H     + H₂ -----> H-C-C-C-C-H
   H   H    H   H                             H  H H  H

[**RoRo**]

I take down notes while my teacher is speaking and this is what I have, some of it just doesn't make sense to me, can someone please go through them and correct me if I am wrong?

It's from the topic Atomic Structure [Unit 1]

1. The p orbital will have less energy compared to the s orbital because s is more stable.

2. p6 has more energy compared to p5 and p3 has more energy compared to p2 because p6 and p3 are more stable compared to p2 and p3.

3. As the distance from the nucleus increases, the energy of the shell increases as it is further apart, so there is less attraction of the electrons by the nucleus and hence it is less stable.

& my fourth question is how do you draw the energy level diagram for lets say Magnesium?
Use this symbol [] to represent the 2 opposite arrows.

Thank you!

[elemis]

how did you do this Ari ?   

You mean how I converted from moldm-3 to gdm-3 ?

All I did was multiply by the molar mass of the compound.

To convert gdm-3 to mgdm-3 I simply multiplied by 1000 because there are 1000 mg in one gram.

[The Golden Girl =D]

okay 9 c

More energy is required to remove the 2nd electron than to remove the 1st electron.
This is because the 2nd electron is being removed from a postive ion,which is smaller than the original atom and experiences greater force of attraction.
Even more energy would be required toremove the 3rd electron and so on.

Hence the IE5>IE4>IE3>IE2>IE1 - should increase

so ofcourse not A or C.

Then if you look at B there is a big jump between the 1st IE and 2nd IE ---->which shows the second electron is being removed from the another inner shell.

But nobles gases have 8 electrons in the outer most shell - which means all the 5 electrons will be removed from the same shell - hence there should no jump in the values between the first 5 IE .

Therefore D - IE increases and no jump in the IE values

This is what I think  

I am sorry if it's confusing  

Highest I.E. is for the Noble Gas , hence the Highest I.E. in the list is for Noble gases hence it's C

11]a) it does make  sense to me

Thanks 

You mean how I converted from moldm-3 to gdm-3 ?

All I did was multiply by the molar mass of the compound.

To convert gdm-3 to mgdm-3 I simply multiplied by 1000 because there are 1000 mg in one gram.

Ahh k , thanks mate