Fortunately, you will probably not have to memorize the shapes of the f orbitals. s, p, d, and f orbitals are available at all higher energy levels as well. The 3dz² looks like a p orbital wearing a doughnut around its waist.Īt the fourth and higher levels, there are seven f orbitals in addition to the 4s, 4p, and 4d orbitals.Ĭounting the 4s, 4p, and 4d orbitals, this makes a total of 16 orbitals in the fourth level. The 3dx² - y² orbital looks exactly like the first group, except that that the lobes are pointing along the x and y axes, not between them. Their lobes point along the various axes. The second group contains the 3dx² - y² and 3dz² orbitals. Each orbital has four lobes, and each of the lobes is pointing between two of the axes, not along them. The names tell you that these orbitals lie in the x-y plane, the x-z plane, and the y-z plane, respectively. The first group contains the 3dxy, 3dxz and 3dyz orbitals. To make sense of the names, we need to look at them in two groups.

At the third level there are a total of nine orbitals altogether. At the third level, there is a set of five d orbitals (with complicated shapes and names) as well as the 3s and 3p orbitals (3px, 3py, 3pz). In addition to s and p orbitals, there are two other sets of orbitals which become available for electrons to inhabit at higher energy levels. There are similar orbitals at subsequent levels: 3px, 3py, 3pz, 4px, 4py, 4pz and so on.Īll levels except the first have p orbitals. The p orbitals at the second energy level are called 2px, 2py and 2pz. This is simply for convenience, because what you might think of as the x, y or z direction changes constantly as the atom tumbles in space. These are arbitrarily given the symbols px, py and pz. The one shown below points up and down the page.Īt any one energy level, we have three absolutely equivalent p orbitals pointing mutually at right angles to each other. Unlike an s orbital, a p orbital points in a particular direction. However, at the second level, there are also orbitals called 2p orbitals in addition to the 2s orbital. At the first energy level, the only orbital available to electrons is the 1s orbital. We call this surface a node or a nodal surface.Ī 3s orbital is even larger, and it has three nodes. There is a surface between the two balls where there is zero probability of finding an electron. It is sort of like a hollow tennis ball.Ī 2s orbital is similar to a 1s orbital, but it has sphere of electron density inside the outer sphere, like one tennis ball inside another. If you look carefully, you will notice that a 1s orbital has very little electron density near the nucleus, but it builds up to a maximum as you get further from the nucleus and then decreases beyond the contour. Now, let’s look at a cross-section of these orbitals. The order of size is 1s < 2s < 3s < …, as shown below. As the energy levels increase, the electrons are located further from the nucleus, so the orbitals get bigger. We call this shape the 95% contour.Īn s orbital is spherically symmetric around the nucleus of the atom, like a hollow ball made of rather fluffy material with the nucleus at its centre. All we can do is draw a shape that will include the electron most of the time, say 95% of the time. Since an electron can theoretically occupy all space, it is impossible to draw an orbital. All we have to do is remember the shapes that correspond to each letter. The letters s, p, d, and f were assigned for historical reasons that need not concern us. The letters go in the order s, p, d, f, g, h, i, j, etc. The letter refers to the shape of the orbital. Thus 1 refers to the energy level closest to the nucleus 2 refers to the next energy level further out, and so on.

The number denotes the energy level of the electron in the orbital. Each orbital is denoted by a number and a letter.

Degenerate atomic orbitals