## Valence electrons

taiyeojeikere-3C
Posts: 30
Joined: Fri Sep 28, 2018 12:26 am

### Valence electrons

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?

Brandon_Tran_2E
Posts: 63
Joined: Fri Sep 28, 2018 12:23 am

### Re: Valence electrons

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.

Josceline 3J
Posts: 33
Joined: Fri Sep 28, 2018 12:21 am

### Re: Valence electrons

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?

Claire Guo 1B
Posts: 32
Joined: Fri Sep 28, 2018 12:15 am
Been upvoted: 1 time

### Re: Valence electrons

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.

Alli Hinmon 3E
Posts: 30
Joined: Wed Nov 08, 2017 3:00 am

### Re: Valence electrons

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.

Nicholas Le 4H
Posts: 74
Joined: Fri Sep 28, 2018 12:24 am

### Re: Valence electrons

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.

Alexa_Henrie_1I
Posts: 61
Joined: Fri Sep 29, 2017 7:03 am

### Re: Valence electrons

We write the d group in electron configurations before p groups because the d state is lower in energy than the p state

Niveda_B_3I
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

### Re: Valence electrons

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).

Ronak Singh
Posts: 31
Joined: Fri Sep 28, 2018 12:16 am

### Re: Valence electrons

Valence electrons are outer shell electrons that are the furthest away from the nucleus.