how do u find the electron configuration of a chloride ion?

Question

aaronq · Answer

what configuration does the Chlorine atoms have in it's neutral state

aaronq · Answer

atom*

aaronq · Answer

no, how many electrons does a chlorine atom have?

anonymous · Answer

17?

aaronq · Answer

yep, so you know it's in group 7, and it has 7 valence electrons. you know that they want to achieve a valence electron count of 8 (because of its stability), so is it easier for the chlorine atom, that has 7 valence electrons, to gain 1 electron, or to lose 7 electrons, to have an "octet"?

anonymous · Answer

whats an "octet"?

aaronq · Answer

it's a name given to a valence electron count of 8, which is what atoms seek to achieve.

anonymous · Answer

just a quick check for me.. an atom and element are the same? pretty much?

aaronq · Answer

an element is species defined by a specific amount of protons, an atom is a particle composed of protons, neutrons, and electrons. 

so their definitions are different, but they can be used interchangeably

anonymous · Answer

ok now back to the original question.. where were we?

aaronq · Answer

so is it easier for the chlorine atom, that has 7 valence electrons, to gain 1 electron, or to lose 7 electrons, to have an "octet"?

anonymous · Answer

to gain 1

aaronq · Answer

okay, now just add one electron to the electron configuration of the neutral atom. (it should look like the nearest noble gas's config)

anonymous · Answer

Argon?

aaronq · Answer

yep

anonymous · Answer

so there are 8 electrons on an chloride ion?

anonymous · Answer

in*

aaronq · Answer

8 valence (outermost) electrons, yes. 
the answer is  $$1s^{2}2s^{2}2p^{6}3s ^{2}3p ^{6}$$  
btw