Is it the picture, or does the patio slope down towards the foundation? This could be worse than the piece that broke off. Looks like someone damaged the foundation when it was built and it finaly moved a little and broke off. Or the J-bolt (metal rod) was installed to close to the edge and that will also happen.
Get a home inspection, but also try to get an engineer home inspector if you can. They can give you more information. Go to American Society of Home Inspectors, ASHI. to find a professional organization. DO NOT hire who the realtor recommends.