Hi. I'm Sean Tvelia, and today we're going to learn how to represent electrons in an electron energy level diagram. Some very simple starters here, we're going to fill electrons from the lowest energy level and we're always going to fill 1 electron at a time until the entire shell or electron orbitals are filled. So to start we're going to use phosphorous 15, which has 15 electrons. So we'll start with the 1S energy level, we put 1 electron in and since it's not filled we can add a second electron. Then we move to the next energy level, we place the third electron, the fourth electron. Then we're going to move to the 2P orbitals and we'll fill each orbital with 1 electron at a time, 5, 6, 7. And since the orbitals are not filled, we'll come back, 8, 9, 10, and move on to the next energy level. 3S, 11, 12, and then for the 3P orbitals, 1 electron at a time in each orbital, 1, 2, 3. And since that's 15 electrons that how we would complete the electron energy level diagram for Phosphorous 15.