Which radius, vander Waal's or covalent, is larger for an atom?

How is the atomic radius of an element actually expressed?

The bond length of HCl bond is 136 pm. Covalent radius of hydrogen atom is 37 pm. What is the covalent radius of chlorine atom?

An element A with atomic number 112 has recently been discovered. Predict its electronic configuration and suggest the group in which this element be placed.

What are the advantages of periodic classification of elements?