I am pretty sure it won't.
Not to mention that it would be tremendously difficult for the average joe to do a processor replacement on a laptop.
If you don't know whether it will work, I am not sure that it is advisable for you to attempt what you are considering.
If you really wanted to pull something off like a processor switch, you would probably want to aim at something like an i5-2520m which is kinda more like an i3-2120 in reality, but at least it is designed to fit laptops.
However, I do want to re-iterate that you may want to opt not to do the project at all.
I am a veritable wizard when it comes to computer hardware and there isn't much at all that would intimidate me, but if I were thinking of doing what you are considering, I would be a bit intimidated.
I can't remember ever hearing of anyone pulling such a thing off, or even attempting it for that matter, and I hear a lot of stuff.
Most people generally consider laptops to be unupgradeable except possibly the RAM and hard drives. For good reason too.
If you have a warranty, I almost guarantee it would be voided by trying to replace a processor.