Mendeleev’s periodic law only accounted for known elements and did not account for undiscovered elements that had yet to be discovered.
Mendeleev’s periodic law was limited in that it did not account for the existence of isotopes, which are atoms of the same element with different atomic masses.
Mendeleev’s periodic law was based on the atomic mass of the element, which is not always a reliable indicator of an element’s chemical properties.
Mendeleev’s periodic law did not take into account the effect of electron shells on an element’s chemical properties.
