What determines whether something is acidic or basic?

The pH of a particular substance depends on the functional groups that it has within its structure. What is a functional group? A functional group is a group of atoms and bonds within a molecule. The way these atoms are joined together determines how the molecule will react in certain circumstances. The functional group helps to determine whether something is acid, low pH, or basic and has a high pH. An example of an acidic functional group is a carboxyl. The carboxyl functional group is acidic because it is a proton (H+) donator when in solution. The carboxyl group will then become COO- An example of a basic functional group is the amino group, this is because it removes H+ FROM the solution, so the amino group becomes NH3+. An example of a molecule in the human body that can be both acidic and basic depending on which solution it is in is the amino acid.