How did the discovery of isotopes to lead to a revised model of atomic structure?

Dalton postulated that atoms of the same elements had the same mass while atoms of different elements had different masses. 

The discovery of isotopes revealed that atoms of the same element did not necessarily have same masses, they could have different masses.

Therefore, the modern periodic table that we use nowadays contains the average atomic mass of all the isotopes found for a given element.

Ifound this on google “these two compounds have a different ionic structure. caesium ion is larger in size when compared to the sodium ion. the charge gets more area to spread out evenly. so caesium chloride has a lower melting point than sodium chloride.” i hope this you for what your looking for