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Naming noncomplex transition metal compounds – HELP!

Na2CrO4
This is sodium chromate (vi)



But why isn’t it called sodium chromium (vi) oxide? You can have iron (ii) oxide and zink oxide…

Why does oxygen have the –ate in this case but not the others?

I have also noticed oxygen can have the suffix -ite... ?! Can someone please explain :frown:

Also, do any other elements have confusingly annoying suffixes, like this, that I should know about?

Help is much appreciated! xxx
Original post by Lissy14
Na2CrO4
This is sodium chromate (vi)



But why isn’t it called sodium chromium (vi) oxide? You can have iron (ii) oxide and zink oxide…

Why does oxygen have the –ate in this case but not the others?

I have also noticed oxygen can have the suffix -ite... ?! Can someone please explain :frown:

Also, do any other elements have confusingly annoying suffixes, like this, that I should know about?

Help is much appreciated! xxx


The issue here is that the compound is ionic and contains a negative ion with the formula CrO42-

This ion is called the chromate ion and to differentiate it from other chromate ions the oxidation state of the chromium atom is also given as a roman numeral in brackets immediately after the ion name, as is the convention.

Hence the ion is called chromate(VI)

This makes the compound sodium chromate(VI)

The -ite suffix is from an old naming system in which ions with atoms of a lower oxidation state than an -ate are called -ite.

Hence:

sulfate SO42- now called sulfate(VI)
sulfite SO32- now called sulfate(IV)

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