If you're asking what element is number 17 on the periodic table the answer is Chlorine. Assuming this is for a chemistry class you should have a periodic table available to you and that would be rather easy to look up.
The element in the Periodic Table that has 85 protons is Astatine. This element is in the Halogen Family (Group 17 in the Table). This group includes the elements Fluorine, Chlorine, Bromine, and Iodine.
The element with the atomic number 85 is Astatine (At). Astatine is a Radioactive Halogen in Group 17(7) of the Periodic Table. Astatine has 85 electrons in 6 shells with 7 electrons in the outer shell. Astatine is the third radioactive element on the Periodic Table.
Bromine is an element on the periodic table. It has an atomic number of 35. It can be found near the right side of the table. Bromine is located in the Halogens group, which is group 7A or 17, and is also in period 4.