What scientific discoveries led to changes in dalton's atomic theory?

The discovery of sub-atomic particles and alimentary particles

Explanation:

For over 100 years Dalton's theory was tested and used to explain the chemical and physical behaviour of atoms. But during the 20th century parts of the thoery were found to be incorrect and therefore disproved because atoms are made up of sub-atomic particles and alimentary particles.

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 !