# Why is it such that calcium carbonate formula is CaCO3 while sodium/potassium carbonate is Na2CO3,K2CO3 respectively?And what is the charge of CO3?Thanks

jerichorayel | College Teacher | (Level 2) Senior Educator

Posted on

To better illustrate this problem, the knowledge of the charges of the ions is necessary.

Na2CO3 is formed when Sodium and Carbonate ions are combined. Sodium ion has a charge of +1 and Carbonate ions has a charge of -2.  Remember the "crisscross" method when dealing with this problem.

`Na^(+1) + CO_3^-2 -> Na_2CO_3`

Same as with K.

`K^(+1) + CO_3^-2 -> K_2CO_3`

In the case for Calcium, it has a charge of +2. When you do the crisscross method, the subscript will have both 2 and it will be cancelled.

`Ca^(+2) + CO_3^-2 -> CaCO_3`

Sources:

pramodpandey | College Teacher | (Level 3) Valedictorian

Posted on

In CaCO3  ,

`Ca^(++)`

`CO_3^(--)`

`` only one Ca required

Na2CO3

`Na^(+)`

`K^(+)`

valency here for Na and K are (+1) and CO3  is (-2)

so we need 2 Na and 2 Potassium molecules.

``