Re: Isoto-oops?

[RuthWeiner@AOL.COM]

Certainly isotopes of an element differ in mass -- that's how they can be separated by a mass spectrometer.  Moreover, isotopically substituted compounds will differ in mass also.  However, macroscopically it almost never matters.  For example, chlorine has two stable isotopes of mass 35 and 37, and we macroscopically treat chlorine as having atomic weight 35.5 (35.5 grams per mole).  Moreover, physically, chlorine gas that is pure Cl-35 behaves just like chlorine gas that is pure Cl-37.  Of course, much of what is generally thought of as "physical" behavior (e.g., conductivity, specific heat) is a function of the outer electronic structure of the element.  To complicate the distinction still further, most of what is dealt with in the macroscopic physical world is compounds, and not pure elements.  For example, the physical behavior of NaCl-35 is indistinguishable from that of !

!

!

NaCl-37.  Besides, macroscopic quantities of any substance contain all the stable isotopes (and long-lived radioactive ones) in the proportions in which they occur.


So you are partly right, but the question can be complicated.


I didn't mean to sound elitist (but maybe I am).


Ruth Weiner, Ph. D.

ruthweiner@aol.com