Question

Explain why the properties of elements as repeated after 2,8,18 and 32 elements as repeated after 2,8,18 and 32 elements in the periodic table

Answer 1

The filling of electrons in an Orbit depends on
$2 {n}^{2} law$
which says the maximum number of electron an orbit can accommodate are given by the formula mentioned above

For n=1
max electron= 2*1*1= 2
for n=2
electron= 2*2*2=8
For n=3
electron= 2*3*3= 18
For n=4
max electron= 2*4*4= 32
hence the answer

Answer 2

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