Please Answer this question if any1 can..
Is the radius of the hydrogen like species (he+,Li2+...) are same as hydrogen i.e 1 ??

Question

jfraser · Answer

No. The number of electrons in each may be the same, but the number of protons pulling on those electrons is different in each atom.

The hydrogen atom has 1 proton pulling on 1 electron.

The He+1 ion has 2 protons pulling on 1 electron.

The Li+2 ion has 3 protons pulling on 1 electron.

As the nucleus gets stronger, it draws that single electron closer and closer. The Li+2 will have the smallest radius of this set.

anonymous · Answer

Thank you Then how would we calculate the radius of these orbits??
What should we take as the value of 'n' in the equaion r=0.529*n2 
??

jfraser · Answer

You are missing part of the equation, it should be:
$$r = 0.529*(n{^2}/Z)$$
The value for n is determined by the number of the energy level, as numbered from closest (n = 1) to farthest (n = infinity). In each case here, n = 1, since a single electron will occupy the first energy level. The value for Z will be the atomic number of that particular atom or ion. For H, Z = 1; for He+1, Z = 2, and so on...

anonymous · Answer

oh thnx i've got it nw...

anonymous · Answer

Actually i was solvn a problm nd coudnt ans it...
Q)ratio of the radii of the K shell n He+ nd Li2+ is:
a) 3:2 b)2:3 c)1:3 d)3:1

jfraser · Answer

solve for the radius twice, once for He+1, and once for Li+2. Then divide those two answers to get the ratio of the radii

anonymous · Answer

Oh dude i knw tht buh i wanna knw how to solve fr the radius??

jfraser · Answer

r in the equations above is the radius

anonymous · Answer

okay.. buh i wanna knw wht value do we use for "n" in case of He+ nd Li+2?? this is wht i actually wanna knw..

jfraser · Answer

see my original reply

anonymous · Answer

So, eventually for He+ will have n=2 nd ni+2 will hav n=3

jfraser · Answer

No. the "n" for each kind of ion is still 1, because the electron is occupying the lowest (n = 1) energy level, regardless of which ion you are looking at. The Z value for each ion will be different.

anonymous · Answer

ohh... got it.. i'm sucha dumbo thnx anyay..