A fluorine (F) atom gains one electron to become a fluoride ion. Write the symbol used to represent this ion

Please help me I have no idea!!!! Thank you all in advance!

to answer your magnesium ion question :

since an electron has a charge of -1 .. if we gain an electron we have a charge of -1

and if we lose one electron we have a charge of +1 ..

since in this case we lost 2 electrons ..the ion would be represented as Mg2+

:) Hope I helped.

Why not write down what you know:
A fluorine (F) atom gains one electron to become a fluoride ion.
F + e = F-

Really? You should try reading the book.