Question 214498
This is more a chemistry question, but I happen to know a little bit about it. Remember that an <a href="http://en.wikipedia.org/wiki/Ion">ion</a> is simply "an atom or molecule where the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge." (from <a href="http://en.wikipedia.org/wiki/Main_Page">Wikipedia</a>). 



Recall that the charge of an electron is -1 while the charge of a single proton is +1. If there are more protons than electrons, then the atom/molecule is positively charged which makes it a cation. If there are more electrons than protons, then the atom/molecule is negatively charged which makes it an anion. 



To find the net charge, simply subtract the number of electrons from the number of protons to get: 35-38 = -3



Note: this is the same as saying: 38(1)+35(-1) = -3



So the net charge of this ion is -3 which means that it's negatively charged and that it's an anion.