What is the charge on a fluorine ion? explain answer plz

-1 

An ion is an atom which has gained or lost electrons. 
Atoms want to have full outer shells of electrons. 
Electrons are negative. 
Fluorine has 7 electrons in its outer shell. When it gains one to fill its shell it will be made negative.
Thus the charge of a fluorine ion is -1 

Answer earth,water,fire and air;