Jocelynn's Chicken Rice Casserole

Chicken Rice casserole...3 cups of cooked chicken, 2 cups of chopped celery,2/3 teaspoon minced onion, 3/4 cup mayonaise,1 cup cooked rice, 1 teaspoon lemon juice,1 can of water chestnuts,1 can of cream of chicken soup, 1 stick of melted butter...Mix all of the ingredients and then top with 1 cup of Rice Krispies..Bake at 350* for 45 minutes uncovered.