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### Valence electrons

Posted: Sat Oct 27, 2018 11:19 pm
When trying to figure out the amount of valence e- in an atom, are we supposed to figure out the electron configuration first? And is the last shell the valence shell?

### Re: Valence electrons

Posted: Sun Oct 28, 2018 12:45 am
One easy way is at the top of the periodic table, the last digit of the group numbers is usually the amount of valence electrons... Group 1 and 2 have 1 and 2 valence electrons respectively, 13, 14, 15, 16, 17, 18 have 3 , 4 , 5, 6, 7, 8 valence electrons.

### Re: Valence electrons

Posted: Sun Oct 28, 2018 1:11 am
I know that valence electrons are the ones in the outermost shell but can someone please clarify the number of electrons that go in each shell?

### Re: Valence electrons

Posted: Sun Oct 28, 2018 2:24 am
The number of electrons that can fit in each shell (n) is 2n^2. So the first shell can have 2, second can have 8, third can have 18, and so on.

### Re: Valence electrons

Posted: Sun Oct 28, 2018 9:33 am
When dealing with Valence electrons, why is it that the d group is before the P group when we write the configuration (ex: 1s2, 2s2, and so on), I want to better understand the different orbitals conceptually.

### Re: Valence electrons

Posted: Sun Oct 28, 2018 11:44 am
Valence electrons can be determined by looking at their group number at the top. For, example chlorine is in group 7, so thus it has 7 electrons. In cases of ions like Ag+, one should write out the ground state electron configuration to figure out the valance electrons as they differ from the regular format of finding valence electrons. In the case of Ag+, the valence electrons are 4d^10.

### Re: Valence electrons

Posted: Sun Oct 28, 2018 11:55 am
We write the d group in electron configurations before p groups because the d state is lower in energy than the p state

### Re: Valence electrons

Posted: Sun Oct 28, 2018 4:11 pm
The last shell is the valence shell, and the number of valence electrons is the number of electrons in the last shell (determined by n value).

### Re: Valence electrons

Posted: Sun Oct 28, 2018 4:14 pm
Valence electrons are outer shell electrons that are the furthest away from the nucleus.