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Thu 10 May, 2007 02:55 pm
What is the size, in metres cubed (or cm, or w/e) of an oxygen molecule, ie. O2?
An oxygen molecule is 0.29 nanometers in diameter.
From this value, you should be able to calculate the Vol.
An Oxygen molecule is not .290 nm in diameter.
Since atoms are surrounded by electron clouds that don't have a clear edge (they just get weaker and weaker indefinately) the term "diameter" is a difficult one... unless you are talking about the distance from nucleus to nucleus.
If this question is from a chemistry class, there are two possibilities.
One... the instructor is trying to get you to understand the problem with measuring the diameter (or the volume) of an atom because you can't define its edge.
Or... this is a problem about gas law... and you are really supposed to be talking about the volume of a gas (i.e. lots of molecules)... in this case, most of the volume you are measuring is the space between molecules.
It was actually a physics question where I needed the volume of one molecule so I could find the average distance between oxygen molecules at STP. I dont think they wanted that much thought to go into it.
Some values for the O atom:
Atomic radius 60 pm
Atomic radius (calc.) 48 pm
Covalent radius 73 pm
Van der Waals radius 152 pm
(pm=picometer)
The numbers for molecular radius you are giving (without putting too much thought into it) are picometers (that is 10^-12 meters).
The correct numbers for distance between molecules are on the order of (10^-8) meters.
This means the distances we are arguing about will be around 1/10000th of the total.
This is like measuring how many miles a trip will take... and worrying how many inches you travelled leaving your parking space.
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