Introducing The Atomic Orbitals
The orbitals, as commonly recognised, are as follows:
The s orbital is a sphere shape, with the centre at the nucleus. It has no nodes, and is the simplest of the orbitals.
| s orbital |
|---|
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The p orbitals have two "lobes" projecting from the nucleus. They are often described as "dumbbell-shaped". There are three specific p orbitals, each "pointing" along one of the three Cartesian axes. They have one node, which is the flat plane at which their named coordinate equals zero. For example, the px orbital has a node at the plane x = 0.
| px orbital | py orbital | pz orbital |
|---|---|---|
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The d orbitals have a variety of shapes. Three are "double dumbbells" that sit between the named Cartesian axes. Similar to the p orbitals, they have two nodes that are flat planes at which each of their named coordinates equals zero (eg. dxy has a node at the plane x = 0, and another at the plane y = 0).
| dxy orbital | dxz orbital | dyz orbital |
|---|---|---|
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Another d orbital is a "double dumbbell" that points along the x and y axes. Its nodal planes are at y = x and y = -x.
| dx2-y2 orbital |
|---|
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The last d orbital is a "single dumbbell with a donut". Its two nodal planes are actually cones stretching out along the z axis in the positive and negative directions.
| dz2 orbital |
|---|
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There are seven f orbitals : four of them are "triple dumbbells" in a hexagonal pattern, two are "quadruple dumbbells" and one is a "dumbbell with a double donut". Each has three nodal planes cutting across the atom in one direction or another.
These four groups of orbitals: s, p, d and f, are the orbitals most commonly encountered. These are the orbitals that the known elements use when their electrons are in the lowest energy state. However there are nine g orbitals, eleven h orbitals, and many more. These additional orbitals are not used unless the atom is put into a high energy state, such as during a collision with another particle.
Red and Blue?
The images above depict orbitals with blue and red lobes. This is deliberate. We don't need to know very much about Schrodinger's equation but one tiny detail we do need to know is that the wave equation that represents an electron in its orbital has regions of positive (blue) and negative (red) values. This will become important later. This does not mean however that the electron suddenly has a positive charge in some of these regions - the electron is still the same electron everywhere inside its orbital.
- Take a detour to A Closer Look.
- Continue with Explore Atomic Orbitals.
