Answer:
Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, Iodine ( and Astatine ).
An easy way to remember this is to think of the phrase:
Professor Brinclof (BrINClOF), or Br, I, N, Cl, O, F (and Astatine)
Another way to remember:
He Never Orders Fried Clam Brains Immediately
or:
Oh I Have Nice Closet For Brooms