N= 2


2S charge density
1S density
The image on the left is a representation of the N = 2, L = 0 electron orbital. Conventionally this is known as a 2S orbital. Note:
  • The brighter the image the greater the greater the charge density in that region.
  • The image is completely spherically symmetric, as are all S orbitals.
  • The charge density is peaked at two distinct radii.

2S phase  
1S density
This image shows the same orbital as above, but now colour is used to represent the phase of the wave function.The key features to note are:
  • The colour is the same at all angles. i.e. the phase of the wave function does not change as one moves around the atom. This indicates that there is no momentum associated with oribits around the atom.
  • The colour is different in the inner and outer regions. This indicates that momentum is associated with radial motion.


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2P Mz = 0: charge density
1S density
The image on the left is a representation of the N = 2, L = 1, Mz = 0 electron orbital. Conventionally this is known as a 2P orbital. Note:
  • The brighter the image the greater the greater the charge density in that region.
  • The image is lobed. In the view shown, the z-axis vertical, so one lobe is above the nucleus and the other below.
  • The charge density is peaked at just one distance from the nucleus (compare with 3P)

2P Mz = 0: phase 
1S density
This image shows the same orbital as above, but now colour is used to represent the phase of the wave function.The key features to note are:
  • The colour is not the the same at all angles. i.e. the phase of the wave function changes as one moves around the atom. This indicates that there is momentum associated with oribits around the atom.
  • In the view shown, the z-axis vertical. There is no colour change (phase change) associated with motion around the z-axis.


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2P Mz = +1 or -1: : charge density
1S density

The images on the left are representations of the N = 2, L = 1 Mz = +1 or -1 electron orbitals. Conventionally these are known as a 2P orbital. Note:
  • The brighter the image the greater the greater the charge density in that region.
  • The image is shaped like a doughnut. In the upper image, the z-axis vertical. The lower image shows the view seen looking down the z-axis onto the x-y plane.
  • The charge density is peaked at just one distance from the nucleus (compare with 3P)
  • These images look the same for both the Mz =1 and the Mz = -1 orbitals, but as the pictures below, this does not mean the orbitals are the same!

2P Mz = +1 or -1: phase 

This image shows the same orbital as above, but now colour is used to represent the phase of the wave function.The key features to note are:
  • The colour is not the the same at all angles. i.e. the phase of the wave function changes as one moves around the atom. This indicates that there is momentum associated with oribits around the atom.
  • Both images show the view seen looking down the z-axis onto the x-y plane
  • In the upper image, Mz = 1, and in the lower image Mz = -1. You should be able to see that sense in which the phase of the wave function (colour) changes is different in the two images. This corresponds to angular momentum about the z-axis of + and - one unit. (HINT: If you find this difficult to see, look at the red colour: What colour is just to its left in each image?)
  • At a given angle, the colour does not change with radius. This indicates that for electrons in these quantum states, there is no momentum/energy associated with radial motion.


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