solubility

Hi I have a lab in Chemistry 12 where I have to design and conduct an analysis of precipitates that form from the reactions of salt solutions to identify unknown solutions X, Y and Z. We'll be given 2 mL of 10 different salt solutions such as MgCl2, NaCl, etc. Then we're also given 3 unknown...

Can someone tell me if solubility decreases or increases across rows of the periodic table? Solubility in water would be preferred. Thanks