 Okay, so how does the new regime of orbitals match up with the old electron levels? According to Schrodinger's model, each orbital can hold a maximum of two electrons, unlike the shells, the electron levels, which could hold larger numbers. So the new model states that each energy level must be divided into a number of orbitals. Level one could hold a maximum of two electrons, so it only has one orbital. This is known as the 1s orbital. Level two tells you the energy level, it's the first energy level, and s tells you the type of orbital. Level two is able to hold eight electrons, as you know. Since each orbital can only hold two electrons, that means that the second energy level must be made up of four orbitals, each holding two electrons. These four orbitals are the 2s orbital, and three are the orbitals called the 2p orbitals. You can see from this diagram that the three 2p orbitals have exactly the same energy as one another, and that they're slightly higher in energy than the 2s orbital, which means, on average, they're slightly further away from the nucleus. Level three is able to hold 18 electrons, so it must be made up of nine orbitals. They are the 3s orbital, three 3p orbitals, which are slightly higher in energy, and five 3d orbitals, which are higher in energy again. And as you can see from the diagram, each succeeding level can hold more and more electrons, because it's composed of more and more orbitals. You can see there's a pattern here, too. Each level starts with an s orbital, and then it has p orbitals, and then d orbitals, and so on. The thing that all the orbitals of a particular type, all of the s orbitals, or all of the p orbitals, the thing that they all have in common is their geometry. It's not necessary for you to remember these shapes, but I think it's interesting to see them nonetheless. Remember that the surfaces of the shapes in this diagram just indicate the region within which the electrons in that orbital spend most of their time. So all s orbitals are spherical. As you go from 1s to 2s to 3s, and so on, further energy levels that are further away from the nucleus, the size of the sphere increases, meaning the electron spends more time further away from the nucleus. The p orbitals, in contrast, are dumbbell shaped. There are always groups of three p orbitals together, and each one points in a different direction. The d orbitals are even more complicated with combinations of dumbbells and a ring and various things. Okay, that's all for part one. In part two, we're going to learn how to write the electron configurations for atoms using these new orbitals.