I'm building a table and am planning breadboard edges. My concern in wood expansion. I was planning to tounge and groove the joint and secure with glue. Should I be worried about splitting due to expansion? If yes do you have any suggestions?
Breadboard edges are typically joined with a long tenon on the table top and a long mortise on the breadboard. The mortice is longer than the tenon to allow for the expansion of the table top. The tenon is only fixed at one point along its length, usually with a little glue and a pin. Pins though the breadboard at other locations pass through slots in the tenon to allow for expansion. Almost any book you can find on furniture design in your local library will cover this type of joint.
Rigidly gluing the table top into a breadboard will almost surely lead to splitting of the table top.
If you glue the full length it'll have problems with splitting. If you attach a breadboard you'll have to allow for expansion in the width of the table. Typically you should only glue one end or the middle and let the rest of it and float.