Halogens : a group of chemical elements. In photography, three of these, bromine, chlorine and iodine are used with silver to produce light sensitive material.
Deoxyribonucleic Acid [DNA]
Deoxyribonucleic acid is a molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses. DNA and RNA are nucleic acids; alongside proteins, they compose the three major macromolecules essential for all known forms of life.