Give the nuclear symbol for the isotope of potassium for which a=40?

nuclear symbol consists of three parts: 1. the symbol of the element; 2. the atomic number of the element; 3. the mass of the element. for the above problem, the symbol for potassium is k. it's atomic number is 40. the number of protons is 19. so we denote this in the following nuclear symbol; 40 k 19