Van der Waals radius not applicable to most elements?

In summary, the Van der Waals radius does not apply to most elements in wikipedia because it is difficult to measure the intermolecular distances.
  • #1
HappyEngineer
14
0
I was looking at the values for the Van der Waals radius on various elements in wikipedia and noticed that Molybdenum does not have one. I searched a bit and found this site
http://www.webelements.com/periodicity/van_der_waals_radius/
which lists the elements that have a Van der Waals radius. The non-purple ones apparently do not have one.

Why is that? I don't see anything in the definition of the Van der Waals radius on wikipedia which indicates that it doesn't apply to most types of elements.
 
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  • #2
HappyEngineer said:
I was looking at the values for the Van der Waals radius on various elements in wikipedia and noticed that Molybdenum does not have one. I searched a bit and found this site
http://www.webelements.com/periodicity/van_der_waals_radius/
which lists the elements that have a Van der Waals radius. The non-purple ones apparently do not have one.

Why is that? I don't see anything in the definition of the Van der Waals radius on wikipedia which indicates that it doesn't apply to most types of elements.

Perhaps it is due to the inability to measure the intermolecular distances (for whatever reason, e.g. structure). Not sure though.

CS
 
  • #3
So you're saying that they're not filled in because it's difficult to measure?
 
  • #4
From my understanding the simplest way to get the Van der Waals radius is to calculate it using ab initio software. The elements that haven't been calculated then are either not widely used or are too big to have been implemented in the ab initio systems yet. Any element that can form a bond would have to have a Van der Waals radius.
 
  • #5
Funny this question should come up, seeing as I happen to be researching it. The current standards in van de Waals radii come from the most cited paper in the Journal of Physical Chemistry, written by A. Bondi. They still represent the best general, all-purpose radii if one must write in distances and not calculate, even though it was written in 1964. Bondi used mostly x-ray crystallographic data for the purpose. People who have come up with different values do so from a variety of different perpsectives of what a good experiment is to analyze.

Maybe, if I am successful (probably not the way it is going right now...), the entire Periodic Table will be published!
 
  • #6
I noticed an article on wiki, under the Casimir Effect at short range distances, being analysed with the effect of Van der Waals' force. This may be of help to you.
 

FAQ: Van der Waals radius not applicable to most elements?

1. What is the Van der Waals radius and why is it not applicable to most elements?

The Van der Waals radius is a measure of the distance between atoms or molecules when they are not chemically bonded to each other. It takes into account the attractive and repulsive forces between particles. However, it is not applicable to most elements because it is based on theoretical models and does not accurately reflect the real-life behavior of atoms.

2. How is the Van der Waals radius calculated?

The Van der Waals radius is calculated using the Lennard-Jones potential, which is a mathematical model that describes the interaction between particles. It takes into account the size and shape of the particles, as well as the strength of the attractive and repulsive forces between them.

3. Which elements is the Van der Waals radius applicable to?

The Van der Waals radius is applicable to non-bonding atoms or molecules, such as noble gases, which have a stable outer electron shell and do not readily form chemical bonds with other elements. It is also used to describe the distance between molecules in liquids and gases.

4. Why is the Van der Waals radius important in chemistry?

The Van der Waals radius is important in understanding the properties and behavior of atoms and molecules, as it gives insight into their size and how they interact with each other. It is also used in predicting the boiling points and melting points of substances, as well as their solubility and other physical properties.

5. Are there any exceptions where the Van der Waals radius is applicable to elements?

While the Van der Waals radius is not applicable to most elements, there are some exceptions. For example, it can be used to describe the distance between atoms in certain types of chemical bonds, such as hydrogen bonds. It is also applicable to larger molecules, such as proteins and DNA, which have a complex and dynamic structure that can be described using the Van der Waals radius.

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