Where Do Valence Electrons Go in Covalent Bonds?

[Brickster]

In convalent bonds, when the atoms interact to form the bonds, where do the valence electrons, or clouds, exist. Do the simply loop around them in a chaotic figure eight of sorts, or do the electrons spin inbetween them? Is the realitive location of the the val. e-'s even know? And if the electrons do spin in between the atoms, what are the orbiting/spinning around? Is it the combined pulls of the atoms or something occurring between the effected electrons? I know of orbitals, s, p ,d f, and their visualized shapes created, but just don't understand how these orbits could occur without the nucleus mass in the center. Thank you

 

[gravenewworld]

The electrons of an atom are found in the orbitals of that atom. The orbitals are actually functions, which give rise to the shape you commonly see of atomic orbitals. The functions that describe the shape of the orbital come from solving the Schrodinger equation for Psi, i.e. the wave function. The orbitals only tell you where you have the greatest probability of finding an electron, you can not,however, pin point the exact location of an electron at a specific point in time due to the Heisenburg (sp?) uncertainty principle. When atoms form covalent bonds, they overlap their atomic orbitals giving the electrons more "space" to move around, thus decreasing energy. Also you shouldn't think of electrons as being tiny little solid objects that move around, electrons have a duel nature. They are sometimes particles and sometime just waves.

 

[Sirus]

That is true, but for chemical bonding concepts, I think it is more convenient to ignore the wave-particle duality of the electrons. It does not hurt to understand duality, particularly when more advanced chemistry or physics concepts are introduced, but bonding is most easily explained with electrons as particles.

Just a little thing (my opinion). Good answer to the original question, gravenew.

 

[Dual Op Amp]

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

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

 

[so-crates]

Dual Op Amp could you please not cut and paste that generic post whenever someone asks a question about electron orbitals. Thanks.

 

[Dual Op Amp]

...
What, I like it!

Generic?