Why are alkaline earth metals and alkali metals found in nature by themselves?

At element makes up all organic compounds?

#7 how does the structure of amino acids allow them to form a polypeptide? each amino acid has an amino group and a carboxyl group. each amino acid has a hydrogen atom and a carboxyl group. each amino acid has a carboxyl group and an r group. each amino acid has an r group and a hydrogen atom.

What is the equation for calculating rf values