By: Abbey Allen
- Chlorine is a chemical element with symbol Cl and atomic number 17. Chlorine is in the halogen group and is the second lightest halogen following fluorine.
- Bromine is a chemical element with symbol Br, and atomic number 35. It is a halogen. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826.
- Iodine is a chemical element with symbol I and atomic number 53. The name is from Greek ἰοειδής ioeidēs, meaning violet or purple, due to the color of elemental iodine vapor.