Question

explain why the properties of elements are repeated after 2，8，18，32element in the periodic table

Answer 1

Its about a shell { k,l,m,n} which is represented in a atomic structure. The concept of this distribution of electron in a orbit is given by Neil Bohr. he also gave the formula 2n^2 for finding the electron in each shell.

Answer 2

the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.