# Tell me about the subshells in an atom

## Main Question or Discussion Point

can anyone tell me about the subshells in an atom. please do tell me the interrelation ship between them an inozisation energy.

benzun
all for god

## Answers and Replies

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Tom Mattson
Staff Emeritus
Gold Member
Atomic subshells are determined by the allowed standing wave patterns associated with atomic electrons. Whether or not a wave pattern is allowed is determined by such considerations as single valuedness of the wavefunction. Associated with each subshell is an energy, and the ionization energy is the difference between the energy of the electron if it were removed to infinity (usually set to E=0) and the energy of the subshell.

jimmy p
Gold Member
I really wanted to answer this post but i wasnt sure where to start so if you could tell me what you know about subshells and i could see if i can be of any use or not? what level of understanding are we talking about here?

i know very less so you can tell me from the begining.

-benzun
all for God

There are a number of orbitals, with 4 different types of sub-shells, they are arranged like this:

Code:
Orbital 1 - s1
Orbital 2 - s2 & p2
Orbital 3 - s3 & p3 & d3
Orbital 4 - s4 & p4 & d4
Orbital 5 - s5 & p5 & d5
Orbital 6 - s6 & p6 & d6 & f6
Orbital 7 - s7 & p7 & d7 & f7
And that's the limit of them right now, they'll probably make bigger atoms in the future.

Each of those different sub-shells have different energies of electrons associated with them. These sub-shells can be divided again into even smaller, sub-sub-shells, take the p2 sub-shell for instance, it can be divided into p2x, p2y & p2z. Each of these can hold two electrons, but when two electrons share one of these sub-sub-shells they need to be of a higher energy, so the order in which they fill up may be like this:

Code:
p2x(0) p2y(0) p2z(0) - p2(0)
p2x(1) p2y(0) p2z(0) - p2(1)
p2x(1) p2y(1) p2z(0) - p2(2)
p2x(1) p2y(1) p2z(1) - p2(3)
p2x(2) p2y(1) p2z(1) - p2(4)
p2x(2) p2y(2) p2z(1) - p2(5)
p2x(2) p2y(2) p2z(2) - p2(6)
The s sub-shells contain only 1 sub-sub-shell, the p sub-shells contain 3, the d 5 and the f 7.

It gets a little complicated around the d3 area though, because the d3 electrons are of a higher energy than the s4 electrons and so the s4 sub-shell fills up first, however when electrons are removed (ie: for ionisation), it is the s4 electrons which are removed first.

It is handy to think of sub-sub-shells as spheres, where the very first sub-sub-shell (s1) is a sphere surrounding the nucleus, the second sub-sub-shell (s2) is a slightly larger sphere surrounding the first. Then comes the first of p sub-shells (p2) also in the 2nd orbital, this consists of 6 spheres, each one a half of a sub-sub-shell, there are therefore three pairs of spheres, they are called p2x, p2y & p2z. I don't even want to begin describing what the d and f orbitals look like.
Of course, in truth, these sub-sub-shells are not always spheres, especially when you start looking at the f and high d orbitals, their probability surfaces change as the orbitals interact with each other. I say probability surfaces because that's what they are, they are usually 90% probability surfaces, they enclose a volume for which it is expected that the electrons in their orbitals spend most of their time.

So the general rule is that, the higher up an electron is in the atom/ion, the higher the sub-sub-shell it is in, and therefore the more energy it has, and therefore the easier it is to ionise it because you need to supply it with less energy.

Well I think that's a pretty good description of electrons in their orbitals. I hope this has helped you ( ), and to the other guys, if I've made any mistakes (very likely, I've written a lot), please feel free to correct me.

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jimmy p
Gold Member
Oh poo, you answered it!! and a darn sight better than i would, oh well i wouldnt have gone into that much detail cos i havent learned THAT much yet!! i havent learned about sub-sub-shells but i know a little bit bout sub-shells!

I made a mistake, but I made it in so many places that I can be bothered to go back and change it.

See here:

Orbital 1 - s1
Orbital 2 - s2 & p2

Well that should be:

Orbital 1 - 1s
Orbital 2 - 2s & 2p

and the same goes for all the others, the number of the orbital goes before the name of the sub-shell (same goes for sub-sub-shells).

I'm glad that you think I'm so thourough. That means that I stand a good chance of passing my chemistry exam.

The applications of this for physics, is that once you have energy values for various numbers of electrons in each orbital you can calculate things like how much energy is needed to ionise the atom. This is useful for when dealing with photo-electric emission, this applies mainly to metals. A direct result of this are solar panels, I think it is Lithium covalently bonded to something else, which has a very low work function (I think the symbol for the work function is [null]), this means that it gives off electrons readily when exposed to fairly high energy photons, such as visible light.
Calculations are also possible for calculating how far above it's groundstate that an atom is (ie: when electrons gain energy from photons or other sources, they are promoted to higher energy levels, a groundstate atom is one in which all electrons are in the lowest possible energy levels and therefore have no excess energy).

if I think of anything I've missed off, on either the chemistry or the physics side of things, I'll let you know.

Electrons are attracted to protons, but repell electrons. So, instead of all the electrons being bunched up right next to the nucleas, they orbit around the nucleas in shells. These shells can sometimes contain sub-shells. For example, the first shell contains only one sub-shell. As an electron gets further away from it's atom, it must have more "quantum energy." Electrons want to get as close to the nucleas as possible, but according to quantum physics, no to electrons can have the same "quantum energy." So, they orbit in shells. The electrons orbit in orbitals. The sub-shells have orbitals. For example, the 1 shell has an S orbital. Because it's an s orbital and it's the first shell it's labelled 1S. For 1-First shell-, S-S orbital. An S orbital has the shape of a sphere. An orbital wants to fill it's self. Alright, so why would the atom want to have 8 electrons in it's outer most shell, good question. The second shell has two sub-shells. One sub-shell has an S orbital, and the second has three P orbitals. The reason it has three is because they can arrange themselves according to X,Y,Z. Each orbital has only two electrons, because no two electrons can have the same "quantum energy." So, for the valence shell of an atom with two shells, one S orbital and three P orbitals. Two electrons an orbital adds to...8. Hydogen, on the other hand, only has one shell. So, to fill it's valence shell, it only needs two electrons. It already has one - Hydogen = one proton, one electron - so, it only needs to bond with one atom to fill itself. Carbon, on the other hand, has two shells, so it needs 8 to fill it's valence shell. So....

H
H C H Methane!!! CH4.
H

If you were to count it up everyone's filled. The carbon atom has 6 electrons. 2 in it's first shell, and 4 in it's valence shell. It needs 8 in it's valence shell. So, it shares one with hydrogen, and the hydrogen shares one of the carbons. This gives the carbon an extra electron, and the hydrogen it's desired two. The carbon, then, bonds with three more to add to 8.

HOH Water!!! H20. Oxygen has six valence electrons, meaning it needs 2 to gain, which it does with 2 hydrogen molecules.

O=O Oxygen!!! O2.

You're probably wondering, why is there an equals sign between the Oxygen molecules?
This indicated a double bond. Oxygen has six valence electrons, when it bonds with another oxygen, it gets 7. That's not the desired 8. So, it makes a double bond, and they share two electrons each. Which adds to 8.

O
O O Ozone!!! O3. Each one of these atoms share with each other, making 8.

That's covelant bonding!!!
This "quantum energy I told you about is somewhat true. What's really true is that there are four "quantum numbers" that cannot match.
The first is N.
N is the energy of an electron. For example, an electron in the first shell would have an N of 1. An electron in the second shell would have an N of 2. An electron in the third shell would have an N of 3.
N=1, means it's in the first shell.
The second is L. It's actually a greek cursive L kind of like this. l. Okay. This sign is the orbital. L = N - 1. That's the equasion. So, if N = 1, then, L = 0. 0 is an S orbital.
If N = 2, L can equal either 0 or 1. If it is 1, that's a P orbital. If N = 3, then that can be either 0,1 or 2. An S,P or...a D orbital.
Now, the third quantum number is M. It is the orientation of the orbitals, you know XYZ.
M can equal anything between -L and +L. For example if L is 1, then M can equal -1,0,1.
This is 3 different ways of arranging the P orbital.
Now the final one is Ms. For Spin. The spin of the electron can equal - 1/2 or 1/2.

Okay, so let's look at the possible arrangements of some electrons.

N L M Ms
1 0 0 -1/2
1 0 0 1/2 First shell, only can have two electrons.

2 0 0 -1/2
2 0 0 1/2
2 1 -1 -1/2
2 1 -1 1/2
2 1 0 -1/2
2 1 0 1/2
2 1 1 -1/2
2 1 1 1/2 Second shell, eight electrons, but none of them, nor the one's in the first shell have the same 4 quantum numbers.

HOPE YOU UNDERSTAND. IT TOOK ME A WHILE TO WRITE, I'D HATE TO LOSE IT AT THE LAST MOMENT, LIKE THE POWER SHUT DOWN OR SOMETHING. IF YOU UNDERSTAND THIS, YOU WILL UNDERSTAND THE REST.
HERE'S SOME SITES.

http://chemed.chem.purdue.edu/gench...h6/quantum.html [Broken]

http://lectureonline.cl.msu.edu/~mm...od/electron.htm [Broken]

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