Question

What is the name of the compound $Cr_2(CO_3)_3$ ?

Answer 1

To solve the given problem, we should have information about the naming of inorganic compounds, criss-cross rule. When naming an inorganic compound, we first try to break the compound into (+) positively charged cations and (-) negatively charged anions.
The criss-cross rule implies that the number of cations or anions present in a molecule is the valency of opposite anions or cations respectively.

Complete step by step answer:
Step-1 :
Here, we have given the compound $Cr_2(CO_3)_3$ . By hearing the compound, we can say that they have two $Cr$-ions and 3-$CO_3$ ions. Here, Chromium being a metal is a cation, So, $CO_3$ is an anion.
Step-2 :
While naming an ionic compound, the cation is named as the name of their corresponding elements first followed by the name of the anion with -ate if two oxyanions are formed by a single element.
Step-3 :
The cation, Chromium here is a transition metal, so its oxidation state must be identified as $Cr_2(CO_3)_3$, the compound is neutral, so, the overall change will be zero.
So, $2x+3(-2)=0$
$2x=6$
$x=+3$

So, the name of the compound is Chromium (III) Carbonate.

Note:
To name a compound containing a transition metal, we have the general script following as the name of the cation is written in Roman numbers and parenthesis.
Here, while naming the anion, we should be careful whether the anion has oxyanion, a monatomic ion, or so on. The ionic compounds can only be formed by the complete transfer of elaborates between the atoms to create an ionic bond.