I Have Heard of Brownian Motion and I Have Heard that Molecules Vibrate but What Causes the Vibration?

Question

My guess is that it is the bonds between atoms in chemical compounds which vibrate and then these vibrating bonds then cause the whole molecule to vibrate, perhaps in complex ways if there are many inter-atomic bonds. Hence Brownian motion. But does this mean that the atoms in an inert noble gas do not vibrate? Does this difference exist and, if so, what consequences are there at the macroscopic level? Or have I got it all wrong? If so, then please give me the full story.

Answer 1

The full story is that there is energy--the energy of motion--and that large assemblies of atoms, whether connected chemically or not, behave very much like racked poolballs when they are struck by the cueball. The motion of one ball is transferred in part to a second, and this to a third and fourth and... in a cascade of interactions, which even classically can be effectively described as random.

Answer 2

The pool ball analogy is the closest. It's the motion of the molecules themselves, not vibration of molecules or movement of the electrons within the molecules. What you see is the motion of larger, opaque particles which are nudged each time an energetic liquid or gas molecule bumps into it from some random direction. The Brownian motion is that of the larger particle whose motion is changed only a little by each collision from a liquid or gas molecule.

Answer 3

Brownian Motion - The haphazard movement of tiny particles suspended in a gas or liquid resulting from bombardment by the fast moving molecules of the gas or liquid.

(Simply stated, the electrons are "bumping" into one another. This motion increases or decreases due to ambient temperature. The ONLY time Brownian motion ceases is when the temperature is 0 degrees Kelvin, and we have not been able to achieve this.)

Answer 4

Atoms vibrate because the charged particles within them are in constant random motion, regardless of whether they are bonded to other atoms, so yes, even in the inert gasses. In fact, because of the constant and randon motion of electrons, it is impossible to pinpoint their exact location at any given time, we can only predict where they are most likely to be. This is a part of what is called the uncertainty principle. The only way for all motion to stop, is at 0K, or absolute zero, which has never been reached.

Answer 5

The vibrations I think are due to temperature or heat energy. Even though it hasnever been achieved [although some experiments ahve gotten within a few billionths of a degree], isn't the definition of absolute zero the state at which all atomic vibrations of an object of matter cease?

Answer 6

pretty technical stuff here - i think it is the energy within the molecules

Answer 7

a butterfly flapping its wings.