What determines an element´s properties

Chemical properties of each elements are determined as the elements of the electronic configuration and particularly by its outermost valence electrons in addition the total number of electron shells an atom determines to which period it belongs to .

maybe this might help u

well in order to answer this question you have to provide more information < 3

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates