confusion name to formula

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CaminaB_1D
Posts: 63
Joined: Fri Sep 28, 2018 12:16 am

confusion name to formula

Postby CaminaB_1D » Sat Dec 08, 2018 1:52 am

If we are given the name of a coordination compound, for example, potassium hexacyanidochromate(III), I see that the 'ate' in chromate means a negative complex. But when writing out the formula, since there is a potassium(a cation), does it counter the negative charge of the complex and therefore the formula will not have a negative charge? K3[Cr(CN)6]?

305154707
Posts: 31
Joined: Fri Sep 28, 2018 12:16 am

Re: confusion name to formula

Postby 305154707 » Sat Dec 08, 2018 2:10 am

Yes, I think you are exactly correct in that last statement. On their own, the cation and the anionic complex would have their own charges, but since the counter ion (the cation) is acting on the complex, the complex's charge ( in the square brackets) is -3. +3 and -3 cancel out so the whole interaction between the cation and the coordination complex is 0 or neutral.

Richard Ku 4H
Posts: 29
Joined: Fri Oct 05, 2018 12:16 am

Re: confusion name to formula

Postby Richard Ku 4H » Sat Dec 08, 2018 2:21 am

You are correct. The overall charge of the compound will be neutral, and so since potassium has a 3+ charge, the overall charge of the complex will be -3, and hence end in "ate"

Karina Jiayu Xu 4E
Posts: 58
Joined: Fri Sep 28, 2018 12:29 am

Re: confusion name to formula

Postby Karina Jiayu Xu 4E » Sat Dec 08, 2018 1:35 pm

The "ate" refers to only the anion complex. But the overall charge should always be zero.

Jonathan Pai 2I
Posts: 121
Joined: Fri Sep 28, 2018 12:27 am

Re: confusion name to formula

Postby Jonathan Pai 2I » Sat Dec 08, 2018 2:55 pm

It has -ate either because the hexcyanidochromate(III) part, the complex, is negative or because the chromium had just eaten.


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