Chlorine is in group 7. What is the charge on its ions, and is the charge positive or negative?

Chlorine is in Group 7 of the periodic table. Therefore a chlorine atom has 7 electrons in its outer shell. this atom needs one more electron to form an ion with a full outer shell. Hence the ion formed will have a negative charge (adding electrons is adding a negative charge). As there is only one electron being added to the outer shell, the chloride ion formed will have a charge of 1- (and the ion symbol will be Cl^-).