Question

Based on the nature of the side chain, where would you expect to find polar versus nonpolar amino acids?

Answer 1

Amino acids contain an alpha amino group, an alpha carboxyl group, and a side chain.
Amino and carboxyl groups are involved in the peptide bond formation.

Amino acids with polar side chains: Arg, Lys, Asp, and Glu
Amino acids with non-polar side chains: Val, Leu, and Ile

Cellular environment is hydrophilic (Water is the major constituent of live cell -up to 80%-95%)
The hydrophilic environment can interact with hydrophilic groups. It repels hydrophobic groups.
So, proteins fold in such a way that most of their charged/polar amino acids are exposed to the external hydrophilic environment and hydrophobic amino acids buried inside the core.