How does the atomic radius graph from element 1 to 36 show periodicity?

See below.  

Step-by-step explanation:

The graph (shown below) is a series of four lines.

Each line starts at a high value and decreases as the atomic number increases  

They are like a series of waves in which the amplitude rises and falls periodically as the waves go by.

In chemical terms, we would say that the atomic radius varies periodically with increasing atomic number.

the answer is symmetrical : )