Please Explain Electron Configuration?

Question

Hi, I need to know everything about electron configuration. Like what those Numbers, Letters, Subscripts mean.. and how I define certain elements using electron configuration.

Thank you.

Answer 1

All electrons orbit around the nucleus of the atom. The orbitals are called shells. Aside from the first orbital shell which is full with 2 electrons, other orbitals are full with different numbers. When one is full you move on to the next. The first shell "s" is full with 2 electrons. The next, "p" is full with 6 electrons. Next is "d" which is full with 10 electrons and "F" is full with 14. The electron configurations are listed in the following order: 1s, 2s 2p, 3s 3p 4s, 3d 4p 5s, 4d 5p 6s, 4f 5d 6p 7s, 5f 6d 7p. So if you want to find the electron configuration of potassium, for instance, the atomic number is 19 so start with 1s and add 2 to fill that orbital. It is written 1s2. (You've used 2 electrons). Next is 2s which can also take 2 electrons so you write 1s2, 2s2 (now you've used 4 electrons). Next is 2p which can take 6 and since you've already used 4 you have room for 15 more until you reach potassium's 19 so fill the p shell and make it 2p6. Now you have 1s2, 2s2 2p6 ( you've used up 10 electrons). Next is 3s which takes 2 electrons so write 1s2, 2s2 2p6, 3s2. Now by adding 2 more you've used up 12 electrons. Next is 3p. We know that p can take up to 6 electrons and we have 7 more to go to reach 19 so we can fill up that shell with 6 electrons so now you have 1s2, 2s2 2p6, 3s2 3p6 and have used 18 electrons. Next is 4s. We know s can take 2 but we only need 1 more electron so we write 4s1. The end result reads:

1s2, 2s2 2p6, 3s2 3p6, 4s1. Using the sequence of electron configurations and the atomic number of the element you are working on, just keep going through the sequence using the numbers for full orbital shells until you reach the right number of electrons. (Make sure to keep count of the electrons you use as you go along.