Lecture 11/2

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Isis_DW_3G
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Lecture 11/2

Postby Isis_DW_3G » Mon Nov 02, 2020 12:24 pm

When counting up the electrons in Nitrate, I understand that 6(3)=18 then you had the 5 electrons of nitrogen, but why did Dr. Lavelle add 1 extra electron to make 24e-?

Samantha Pedersen 2K
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Re: Lecture 11/2

Postby Samantha Pedersen 2K » Mon Nov 02, 2020 12:29 pm

The overall charge of the nitrate molecule is -1 which indicates that there is an additional electron. Therefore, Dr. Lavelle added one additional electron to the total number of valence electrons from one nitrogen atom and three oxygen atoms to get 24 electrons.

Lucy_Balish_3G
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Re: Lecture 11/2

Postby Lucy_Balish_3G » Mon Nov 02, 2020 12:31 pm

The extra electron added at the end is due to the overall -1 charge of the nitrate ion (NO3-). Nitrate is one of the polyatomic ions and is pretty common, so I would say you should be familiar with the formula and the overall charge.

Annika Tamaki 1E
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Re: Lecture 11/2

Postby Annika Tamaki 1E » Mon Nov 02, 2020 12:34 pm

The minus sign in the formula NO3^- indicates that there is an extra electron. Therefore, he had to add that electron to the total number found from N and the 3 O's.

Alara Aygen 3K
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Re: Lecture 11/2

Postby Alara Aygen 3K » Mon Nov 02, 2020 12:46 pm

You also need to think about the overall charge of the molecule. In NO3^- , it is minus 1. For example, in SO4^-2 it is -2. If the overall charge is negative you add that number of electrons to the other electrons to find the total electrons. If the overall charge is + (e.g. NH4^1) you substract that number from the other electrons to find the total electrons.
Hope that helps!

lwon Dis2I
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Re: Lecture 11/2

Postby lwon Dis2I » Mon Nov 02, 2020 12:56 pm

In the SO4 molecule, I know the final charge is -2, but how does it all add up if sulfur's formal charge is 0 and all four oxygens formal charge is -1? So (4(-1)+0)=-4 but not -2. Can someone explain how summing up the total charge of the molecule works using formal charge?


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