Cho hợp chất XY₂ tạo bởi 2 nguyên tố X, Y,Z, có hai đồng vị: ⁷⁹Y chiếm 55% số nguyên tử Y và đồng vị ⁸¹Y. Trong XY₂ phần trăm khối lượng của X là bằng 28,51% Tính nguyên tử khối trung bình của X, Y

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.