What is the halogen in period 5? it has six letters

Simple,

take a look at your periodic table, if you have it labeled look at the Halogen

Group, it includes: Flourine, Chlorine, Bromine, Iodine, and Astatine.

Now, a period on the periodic table is read from left to right, and goes

down the rows of the periodic table.

Go to Period 5, go all the way to the Halogens, what is there?

Iodine.

Thus, your answer.