I can't my head round this and wondered if anyone can help me! When filling electron orbitals and using the building up order (1s2, 2s2...etc) I don't understand the way the d orbitals fill. I get everything else about it but; e.g. chromium. The configuration is [Ar]3d4, 4s2 but why is it not just [Ar] 3d6? Why does the 4s get electrons when the 3d is not yet completely filled? Can someone please explain this :)
2006-10-02 09:21:01 · 9 answers · asked by Showaddywaddy 5 in Science & Mathematics ➔ Chemistry
The s subshell is more stable than the d subshell of the shell below. In other words 4s is a lower energy state than 3d. So 4s1 is lower energy than 3d1.
The exception being that a half filled or full d subshell is more stable than a filled s subshell so while vanadium is 1s2 2s2 2p6 3s2 3p6 4s2 3d3
Chromium is 1s2 2s2 2p6 3s2 3p6 4s1 3d5.
3d5 is a lower ground state than 4s2.
Ahh now I'm having horrible flash backs of molecular orbital lectures. It's all to do with the shape of the different d orbitals compared to the s orbitals but I wouldn't worry about it too much. If you do a chemistry degree, you'll have the fun job of drawing them all and then working out what happens when they mix with orbitals from other atoms, but until then just because... works as a good answer.
2006-10-03 05:18:45 · answer #1 · answered by Ellie 4 · 0⤊ 1⤋
Prof Jack's link is very good.
Sometimes it is easier just to accept the way the world is rather than question it - especially at this early stage.
The energy levels can be explained by the proximity of the orbitals to the nucleus.
You could imagine a series of buildings the first one being a pub - the nucleus. Then along the street are some places that people live. Start off with a bungalow with a twin room and as the number of electron orbitals/beds increases the size of the house will increase but the bedrooms will be located upstairs. At some stage it will be easier to get home from the pub and go to the bedroom on the ground floor of the fourth house than a bedroom upstairs, maybe a couple of floors, in the third house. This is the way electrons work - they are lazy. Sometimes they get excited and crazy things happen, like they go and stay in the fifth house when they know they shouldn't - but that my friend is another lecture!
2006-10-03 01:16:22 · answer #2 · answered by advent m 3 · 0⤊ 1⤋
It is more chemically stable for the element to fill the 4s oribtals rather than the 3d orbitals as the 4s orbitals are lower in energy and the element will be more chemically stabiler.
2006-10-04 00:53:53 · answer #3 · answered by dessiprincess 1 · 0⤊ 0⤋
The 4s orbital will actually fill before the 3d orbital. Here's a diagram that shows the filling order:
http://www.meta-synthesis.com/webbook/30_timeline/orbitals2.html
2006-10-02 09:25:25 · answer #4 · answered by Anonymous · 0⤊ 1⤋
The reason that the 4s fills before the 3d is because it has a slightly lower energy level.
2006-10-02 09:31:40 · answer #5 · answered by science teacher 7 · 0⤊ 1⤋
4s fills before 3d as it requires slightly less energy to fill 4s than 3d. half filled orbitals are also much more stable than full ones.
2006-10-02 09:54:57 · answer #6 · answered by will t 2 · 0⤊ 1⤋
The 4s recieves electrons when the 3d is not completely filled due to 4s requiring less energy.
look on this site, has good diagrams and stuff to show you, it helped me when i was stuck on this.
http://www.knockhardy.org.uk/assets/AS1AT.PDF
the site itslef is excellent:
http://www.knockhardy.org.uk/sci.htm
2006-10-02 09:28:15 · answer #7 · answered by prof. Jack 3 · 0⤊ 1⤋
Way to difficult for me
2006-10-02 12:10:27 · answer #8 · answered by Anonymous · 0⤊ 1⤋
if you don't understand ask your teacher
2006-10-02 09:29:20 · answer #9 · answered by Anonymous · 0⤊ 2⤋