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Science > Chemistry

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Post here for help

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Does anyone here understand electron configurations?! My teacher is horrible and expects us to know how to set them up off the top of our heads, but she never explained how to do it!

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Being able to write electron configurations of an atom is necessary to ace a chemistry class. Writing them can seem hard, but they are actually easy if you know the basics.

1. Find out how many electrons the atom has. On the periodic table, the atomic number is the number of protons of the atom, and thus equals the number of electrons in an atom with zero charge.

2. refer to the chart
The s orbital set (any number followed by an "s") contains a single orbital, and by Pauli's Exclusion Principle, a single orbital can hold a maximum of two electrons, so each s orbital set can hold two electrons.
The p orbital set contains three orbitals, and thus can hold a total of six electrons.
The d orbital set contains five orbitals, so it can hold ten electrons.
The f orbital set contains seven orbitals, so it can hold fourteen electrons

3. Put one electron into the highest energy orbital available, starting with 1s (holds a maximum of two electrons). Be careful! Do not fill the orbitals in the order shown in the chart! Fill the orbitals in this order (the number following the orbital set is the maximum number of electrons it can hold):

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10
Note: Energy level changes as you go up. For example, when you are about to go up to the 4th energy level, it becomes 4s first, then 3d. After the fourth energy level, you'll move onto the 5th where it follows the order once again. This only happens after the 3rd energy level!

4. Once you've put every electron into an orbital (according to the order), write the configuration as shown at the end of step 3, except, write the number of electrons that are in the orbital set instead of the numbers shown (they are shown as completely filled). So, an uncharged antimony atom's electron configuration would be 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p3. Notice that the number following 5p isn't 6, but three. That's because only three electrons are in the orbital set, so the orbital set is not completely occupied (it lacks three more electrons).

message 4: by (last edited May 03, 2010 05:34PM) (new)

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message 6: by (last edited May 03, 2010 05:35PM) (new)

Yeah, thats basically what our text book said, but it doesnt really help, you know! Cause of exceptions and stuff, and the weird rules! Gah! Thanks though!

message 7: by (new)

The videos are easier to understand!

message 8: by (new)

Ok, thanks! I cant watch them now, but I'll be sure to check them out soon!

message 9: by (new)

ok!

message 10: by (new)

lol!

message 11: by (new)

I took Chem Junior year. I really enjoyed it!

message 12: by (new)

☆★♫∂αιѕу♫★☆ wrote: "yes laugh all you want jen :P"

i'm not laughing at you!

message 13: by (new)

:)

message 14: by (new)

Well, I can help and so can Jen.