[Chemistry4me]

The electron configuration of an atom or ion can be written in a way that shows:
•the energy levels of the electrons
•the orbitals occupied by electrons
•the total number of electrons in that atom or ion.

For example, sodium has 11 electrons. Its electron configuration is:
1s²2s²2p⁶3s¹
The superscipts ²²⁶¹ gives the total number of electrons. The letters s and p descirbe the orbitals involved, and the large numbers 1 (K), 2(L) and 3(M) descirbe the energy levels.
Nearly done! [] You still with me? []

[erickejah (OP)]

yep

[Chemistry4me]

Electrons fill orbitals of lowest energy first. The order of in which electrons fill sublevels is:
1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → 6s → 4f → 5d → 6p → 7s → 5f → 6d

Now, you will notice that the 4s orbital actually fills before the 3d orbitals, as I have shown in the diagram. So the electrons enter the N shell before the M shell is filled up. Does that explain it to you? If you want me to do the ruthenium example, I can show you.  You can see that the P shell actually gets some electrons before the N shell is even filled up ! (6s filled before 4f)

[Chemistry4me]

I forgot to add, the fourth sublevel consists of 7 orbitals which are called f orbitals.

[erickejah (OP)]

WoW, so that is how it works,, that is very interesting. thanks for sharing that with me i feel way smarter now []. so where did u learn all this?

[erickejah (OP)]

do those letters stand for anything?

[Chemistry4me]

Huh? What do you mean? In school of course! [] [] This ins't exactly rocket science, no offense intended dude  []

If you want me to do the ruthenium example, I can show you. []

Even better, why don't you try it yourself.

[Chemistry4me]

Historical names:
s = sharp
p = principal
d = diffuse
f = fundamental

[erickejah (OP)]

ok ill try

[Chemistry4me]

I just going to pop out for a little while, nice to chat erickejah!

[erickejah (OP)]

First  ruthenium has 44 electrons:

I will use 4 shells because they add up to 60 and 44 can fit in there.
 1st shell: (max2)
1s^2
2nd shell: (max8)
2s^2_2p^6
3rd shell: (max18)
3s^2_3p^6_3d^10
4th shell: (max32)
4s^2_4p^6_4d^8

Now ill fill the spaces in between, from the s to f

[erickejah (OP)]

if the 44 electrons fit in the 1st four shells why did they added the 5th one?
like they show in this http://www.webelements.com/ruthenium/atoms.html web.

[Chemistry4me]

Remember:

Electrons fill orbitals of lowest energy first. The order of in which electrons fill sublevels is:
1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → 6s → 4f → 5d → 6p → 7s → 5f → 6d

[Chemistry4me]

1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → 6s → 4f → 5d → 6p → 7s → 5f → 6d

Ruthenium: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶4d⁷5s¹.

Aha, ruthenium wasn't a good one to choose, because what I've told you sort of goes out the door!

[Chemistry4me]

I should also have added that: if there are orbitals of the same energy in a sublevel, the electrons will fill them singly until there is one electron in each orbital. In this way, electron-electron repulsion is minimised. For example nitrogen's electron configuration is: 1s²2s²2p³ and if you think back to that diagram, there will be 2 electrons in the first red box (1s²), 2 in the orange box above that (2s²) but the other three orange boxes will have one electron each instead of two in the first one, one in the second and none in the third.

[erickejah (OP)]

i got it now  [] [] [8D] [8D], i feel smart. tx for the explanation I'm sure u have gain prestige in this forum. not much people has that patience. []

[Chemistry4me]

No worries erickejah [], any time! []