Chemistry: Post your doubts here!

[anishh]

HO2CCH(OH)CH(OH)CO2H + Ca(OH)2 --> HO2COOCCH(OH)CH(OH)COO-Ca2+h2o

 

[Amy Bloom]

Ty

most welcome!

 

[istudent]

What is sheilding effect

 

[smzimran]

What is sheilding effect

The electron shielding effect is the effect where core electrons block valence electrons from the nuclear charge of the nucleus.
Simply put, the shieding effect is inside electrons blocking outside electrons from getting the positive charge

Positive and negative charges attract each other so the more effective charge the electrons get, the more attraction there is between the nucleus and the outer electrons. So as the effective nucleur charge increases, the atom and it's radii becomes smaller

So as the shielding becomes stronger, the nucleur charge decreases and the size of the atom increases

More shielding, bigger atom

 

[Amy Bloom]

The electron shielding effect is the effect where core electrons block valence electrons from the nuclear charge of the nucleus.
Simply put, the shieding effect is inside electrons blocking outside electrons from getting the positive charge

Positive and negative charges attract each other so the more effective charge the electrons get, the more attraction there is between the nucleus and the outer electrons. So as the effective nucleur charge increases, the atom and it's radii becomes smaller

So as the shielding becomes stronger, the nucleur charge decreases and the size of the atom increases

More shielding, bigger atom

I quote this line:
as the shielding becomes stronger, the nucleur charge decreases and the size of the atom increases
U mean as there are more electrons inside, so more shielding, hence size of atom increase right?
so what's the difference between nuclear charge and effective nuclear charge?

 

[smzimran]

I quote this line:
as the shielding becomes stronger, the nucleur charge decreases and the size of the atom increases
U mean as there are more electrons inside, so more shielding, hence size of atom increase right?
so what's the difference between nuclear charge and effective nuclear charge?

The line you quoted means the trend...
and effective nuclear charge is the net charge (protons - electrons)

 

[Amy Bloom]

The line you quoted means the trend...
and effective nuclear charge is the net charge (protons - electrons)

and the nuclear charge?

 

[smzimran]

and the nuclear charge?

only proton charge!

 

[Amy Bloom]

only proton charge!

Okay thanks for clearing that doubt in me

 

[nafis shahRiyar]

guys i need AS level chemistry notes on the 2013 syllabus; my school teacher is not good so i need them faast !!
thanks in advance

 

[Abrar Hasin Kamal]

I NEED NOTES FOR CHEMISTRY AS LEVEL ON THE FULL SYLLABUS FOR 2013 !!!!!!!!! PLZZZZ HELP ASAP!!!!
BTW ! NAFIS ...HEY MAN!

 

[Amy Bloom]

Guys I have some MCQs which are troubling me. can u give me some explanations?

 

[VelaneDeBeaute]

Amy Bloom ; The fourth question was really simple. All you can do, to make the process the easiest, is to find out the number of electrons and protons and neutrons, and then compare them according to what the question asks for!
I'm giving the compositions.
(A) Its D- so its gained an electron; which makes it to 2 e-s, 1 p and 1 n. There are more e-s than p but there are equal number of p and n, so this ain't the best possible answer.
(B) He +ive has lost an electron, so it has 1e, 2p and 2n. Wrong again because we wanted e>p>n, but here, e<p and p=n.
And so on!
I hope you'll work this out yourself now! Good Luck!

For the sixth question you must see that option 3 is totally wrong - both do not contain 32 e-s. Option 2 is wrong again, for introduction of a neutron by no means should decrease the number of protons present already. Option 1 is the only one corrrect as you can make the arithmetic calculation there - Phosphorus has more neutrons than Sulphur. So the correct option, in my opinion, is D!

 

[Amy Bloom]

Amy Bloom ; The fourth question was really simple. All you can do, to make the process the easiest, is to find out the number of electrons and protons and neutrons, and then compare then according to what the question asks for!
I'm giving the compositions.
(A) Its D- so its gained an electron; which makes it to 2 e-s, 1 p and 1 n. There are more e-s than p but there are equal number of p and n, so this ain't the best possible answer.
(B) He +ive has lost an electron, so it has 1e, 2p and 2n. Wrong again because we wanted e>p>n, but here, e<p and p=n.
And so on!
I hope you'll work this out yourself now! Good Luck!

Hey thanks loads , but how do u count the number of protons and neutrons in the diatomic or triatomic particles like OH- and D3O+ ?
! hey, could u solve the other questions, i got stuck in them

 

[VelaneDeBeaute]

Amy Bloom! ^I was editing the post when you just liked it! Check again!

 

[VelaneDeBeaute]

Hey thanks loads , but how do u count the number of protons and neutrons in the diatomic or triatomic particles like OH- and D3O+ ?
! hey, could u solve the other questions, i got stuck in them

Well! You see - e.g. in OH-, you count how many electrons are there in the neutral atom? 8 + 1 = 9 ryt? And -ive aign indicates there has been a gain of 1e, so just add 1 e- there. This is the simplest way.
For D3O+, each D has 1e, so 3Ds will have 3e-s. O has 8 electrons which makes it to a total of 8 + 3 = 11. Now a positive sign = 1 electron lost, so subtract one electron from 11, leaves you with 10 e-s.

 

[Amy Bloom]

Well! You see - e.g. in OH-, you count how many electrons are there in the neutral atom? 8 + 1 = 9 ryt? And -ive aign indicates there has been a gain of 1e, so just add 1 e- there. This is the simplest way.
For D3O+, each D has 1e, so 3Ds will have 3e-s. O has 8 electrons which makes it to a total of 8 + 3 = 11. Now a positive sign = 1 electron lost, so subtract one electron from 11, leaves you with 10 e-s.

Hey thanks a lot. its definitely clearer to me now.

 

[convent2012]

which atom has three unpaired electron ??
A) Al
B) Se
C) Cr
D) Co
plz do explain .....

 

[Bikalpa kattel]

guys when will May june 2012 past papers will be out? please upload here yaar..

 

[Ahmed Khider]

guys when will May june 2012 past papers will be out? please upload here yaar..

Here>>>

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