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Re: energy in the tank



Daniel Schroeder2 wrote:

You could say that the _bonding_process_ (not the bond
itself) is exothermic to the tune of 4.5 eV and I wouldn't
have a problem with that.

That's just a jargonny way of saying that the bond stores
-4.5 eV.

Ah, if you consider "the bond" to be nearly
synonymous with "the bonding process" then it's
clear why we've been misunderstanding each other.

I think of the bonding process as something that
might have occurred 400 years ago, and was fully
complete at that time. When it occurred, it was
exothermic. But I don't care. I wasn't there.

In contrast, I think of the bond as something that
sits there now, a more-or-less tangible thing that
has a size and a shape and a location. I can
add energy to it. If I add enough energy to it,
in a particular way (!), I can reach the continuum
energy level corresponding to isolated neutral
atoms, which you insist on calling "the"
mandatory zero-energy level, but which I sometimes
choose to call the 100eV level.

To drive home the arbitrariness of these energy
level labels, note that I can add energy to the
bond in another way that leads to ionization,
producing a continuum state containing an electron
and an H2+ molelcular ion. This continuum is a
whole lot more than 4.5 volts above the molecular
ground state. More than 20 if I recall correctly.

Bottom line: There is nothing special about any
of the aforementioned states. None of them has
any special claim on the zero-energy label.