It is always appropriate and appreciated when you give your employer a two-week notice letter. This gives them the opportunity to fill your vacancy and it shows that you are a responsible adult. You should always include in the letter the reason that you are leaving, but be tactful. Thank them for all of the opportunities that they've given you and express that you have enjoyed being part of
. their team. The letter should be addressed to your immediate boss and a CC can go to a department supervisor if necessary. Giving the 2 week notice may help you to get a more favorable reference from them if you ever need one.