[meiyuen]

how many planar nodes are associated with each of the following orbitals?
a)2s   b)3d   c)5d

i dont know what planar nodes is about,so can someone pls explain the planar nodes to me instead of giving me answer directly.....thank you

[Schrödinger]

A planar node is an entire plane where the probability of finding the electron is zero. Consider a p_z orbital. It is a dumbell shaped orbital centered on the origin. (look up some google image for better understanding through visualization). The planar node/nodal plane here is the xy plane, i.e, plane formed by x and y axes.

I hope you know this already.
Now let's take 3d as an example. How many 3d orbitals are there and what are they? Once again, look up google images for better visualization of these orbitals. Now, what can you say (based on the paragraph above on p-orbitals) about this one now? In what way are the d-orbitals similar to p-orbitals?

[EpicWinston]

Schrödinger nailed it. Yea go to google images you have to see it to fully understand it. When you look up an image of a p orbital, notice that it is shaped like a dumbbell. The region in the middle is called a node (there are no electrons there and there never will be). It is also good to keep in mind that when you are looking up these images the weird looking lobes is merely the probability of where an electron would be.

[outman]

planar nodes is where the Electron cloud density is zero

 Calculation methods:  n-l-1
 n:Principal quantum number
 l:Azimuthal quantum number

[meiyuen]

Are radial node and planar node the same?

[outman]

planar node=radial node+the angle part of the node ?  right?

sorry about my mistake.

if so, the formula should be : n-1.

[Schrödinger]

The formulae for the nodes are :
n-l-1 radial nodes
l radial nodes
So, total nodes = n-1.

And to answer

Are radial node and planar node the same?

No they aren't. A radial node occurs at a particular radius, kinda like a 'sphere' (only the surface) of zero probability. A planar node is kinda like a 'sheet' of zero probability.

[meiyuen]

There are 5 orbitals in 3d,which are dxy,dxz,dyz,dx2y2 and dz2.
As what u said,the planar node is the xy plane only, or plane formed by either x or y axes olso consider as planar node?so 3d orbitals has 1 planar node or 4 planar nodes?

d-orbital and p orbital are similar because there are both having dumbbell shape right?

[Schrödinger]

As what u said,the planar node is the xy plane only

This is true for p_z orbital only.

d-orbital and p orbital are similar because there are both having dumbbell shape right?

I said they were similar due to the dumbbell shaped lobes. But for a p-orbital there is only 1 dumbbell. For a d-orbital, there are 2 such structures (that is, 4 lobes). Now look at the orbitals again.

[meiyuen]

but it didnt mentioned x,y or z.
so i how i know how many planar node are there?
we are not seeing the planar node based on x,y and z?

[Schrödinger]

Doesnt matter. All the d-orbitals are degenerate. Hence, they will have the same number of nodes. Don't worry about that right now. Take this for granted.

Now, consider any one of the five 3d-orbitals you have in hand. Let's take dxy. What are its nodal planes?

[meiyuen]

Now, consider any one of the five 3d-orbitals you have in hand. Let's take dxy. What are its nodal planes?
[/quote]

z

[Schrödinger]

z is an axis. A nodal plane would be made of 2 axes which create the plane. For example, the yz plane is made of y and z axes.

d_xy has yz plane as one of its nodal planes. http://wikis.lawrence.edu/download/attachments/295337/FG06_023.gif
Find the other.

[meiyuen]

i am quite confusing with the x,y and z
but my lecturer taught us an easier way which is the nodal planes is depend on the angular momentum quantum number,l
let say the l for 2s orbital is 0,so it has 0 planar nodes;the value of l for 3d = 2, so it has 2 planar nodes;while the 5f has a l value of 3,so it has 3 planar nodes....
but i am quite curious about what are there for those planar nodes....

[Schrödinger]

Yes. This is quite right. The l values do indeed decide the number of angular/planar nodes. But in order to see those nodes for yourself, you'll have to refer to diagrams of orbitals like I've been telling you.