What’s the difference between 2 Ca and Ca₂?

Explanation:

2Ca is the elemental form of calcium. There are 2 mols of calcium in whatever equation you are talking about.

Ca_2 means that there are 2 ions of Calcium making up something like

Ca3(PO4)2 means that you have the compound Ca3(PO4)2 with 2 mols of PO4 and 3 moles of Ca

It is hard to come up with something composed of Ca2 because unless the other ion is odd, the 2 will divide into something.

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !

what does the table look like