Hydrogen: molecular or atomic?

http://antwrp.gsfc.nasa.gov/apod/ap071224.html

Please read the caption.

" Sprawling across hundreds of light-years, emission nebula IC 1396 mixes
glowing cosmic gas and dark dust clouds. Stars are forming in this area,
only about 3,000 light-years from Earth. This detailed view was created in
light primarily emitted by hydrogen gas, recorded through a filter that
narrowly transmits a wavelength characteristic of glowing hydrogen atoms in
the nebula. "

Now look at this:
http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html

"This spectrum was produced by exciting a glass tube of hydrogen gas with
about 5000 volts from a transformer. It was viewed through a diffraction
grating with 600 lines/mm."

Do the chemists agree with the astronomers that the hydrogen GAS is atomic
as opposed to molecular?

"Androcles" wrote in message . uk...
http://antwrp.gsfc.nasa.gov/apod/ap071224.html

Please read the caption.

" Sprawling across hundreds of light-years, emission nebula IC 1396 mixes
glowing cosmic gas and dark dust clouds. Stars are forming in this area,
only about 3,000 light-years from Earth. This detailed view was created in
light primarily emitted by hydrogen gas, recorded through a filter that
narrowly transmits a wavelength characteristic of glowing hydrogen atoms in
the nebula. "

Now look at this:
http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html

"This spectrum was produced by exciting a glass tube of hydrogen gas with
about 5000 volts from a transformer. It was viewed through a diffraction
grating with 600 lines/mm."

Do the chemists agree with the astronomers that the hydrogen GAS is atomic
as opposed to molecular?

And if he doesn't like the chemist's answer, he'll give you something
like this:
http://groups.google.com/group/sci.p...33444b6d790e9f
A snappy new year indeed.

Dirk Vdm

Androcles wrote:
http://antwrp.gsfc.nasa.gov/apod/ap071224.html

Please read the caption.

" Sprawling across hundreds of light-years, emission nebula IC 1396 mixes
glowing cosmic gas and dark dust clouds. Stars are forming in this area,
only about 3,000 light-years from Earth. This detailed view was created in
light primarily emitted by hydrogen gas, recorded through a filter that
narrowly transmits a wavelength characteristic of glowing hydrogen atoms in
the nebula. "

Now look at this:
http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html

"This spectrum was produced by exciting a glass tube of hydrogen gas with
about 5000 volts from a transformer. It was viewed through a diffraction
grating with 600 lines/mm."

Do the chemists agree with the astronomers that the hydrogen GAS is atomic
as opposed to molecular?


Hydrogen atoms and molecules have different spectra, and
they are the same for each regardless of whether the light
comes from a discharge in a laboratory or from space. (But
the Doppler shift must be taken into account when the light
source is moving relative to the observer.) The list of
wavelengths at the Web site you gave is what is emitted by
hydrogen atoms. Chemists and physicists agree with this.

On Jan 2, 12:25 pm, Marvin wrote:
Androcles wrote:
http://antwrp.gsfc.nasa.gov/apod/ap071224.html

Please read the caption.

" Sprawling across hundreds of light-years, emission nebula IC 1396 mixes
glowing cosmic gas and dark dust clouds. Stars are forming in this area,
only about 3,000 light-years from Earth. This detailed view was created in
light primarily emitted by hydrogen gas, recorded through a filter that
narrowly transmits a wavelength characteristic of glowing hydrogen atoms in
the nebula. "

Now look at this:
http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html

"This spectrum was produced by exciting a glass tube of hydrogen gas with
about 5000 volts from a transformer. It was viewed through a diffraction
grating with 600 lines/mm."

Do the chemists agree with the astronomers that the hydrogen GAS is atomic
as opposed to molecular?

Hydrogen atoms and molecules have different spectra, and
they are the same for each regardless of whether the light
comes from a discharge in a laboratory or from space. (But
the Doppler shift must be taken into account when the light
source is moving relative to the observer.) The list of
wavelengths at the Web site you gave is what is emitted by
hydrogen atoms. Chemists and physicists agree with this.

If I were to hazard a guess what's on Androcles' mind,
it would be that he thinks hydrogen gas should be composed
of H2 as it is here on earth, not atomic H. Why would
atomic H predominate in deep space?

And if I were to hazard a guess as to the answer, it
would be because hydrogen atoms don't get a lot
of chances to collide with each other at these
densities.

- Randy

On Jan 2, 8:32 am, Randy Poe wrote:
On Jan 2, 12:25 pm, Marvin wrote:



Androcles wrote:
http://antwrp.gsfc.nasa.gov/apod/ap071224.html

Please read the caption.

" Sprawling across hundreds of light-years, emission nebula IC 1396 mixes
glowing cosmic gas and dark dust clouds. Stars are forming in this area,
only about 3,000 light-years from Earth. This detailed view was created in
light primarily emitted by hydrogen gas, recorded through a filter that
narrowly transmits a wavelength characteristic of glowing hydrogen atoms in
the nebula. "

Now look at this:
http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html

"This spectrum was produced by exciting a glass tube of hydrogen gas with
about 5000 volts from a transformer. It was viewed through a diffraction
grating with 600 lines/mm."

Do the chemists agree with the astronomers that the hydrogen GAS is atomic
as opposed to molecular?

Hydrogen atoms and molecules have different spectra, and
they are the same for each regardless of whether the light
comes from a discharge in a laboratory or from space. (But
the Doppler shift must be taken into account when the light
source is moving relative to the observer.) The list of
wavelengths at the Web site you gave is what is emitted by
hydrogen atoms. Chemists and physicists agree with this.

If I were to hazard a guess what's on Androcles' mind,
it would be that he thinks hydrogen gas should be composed
of H2 as it is here on earth, not atomic H. Why would
atomic H predominate in deep space?

And if I were to hazard a guess as to the answer, it
would be because hydrogen atoms don't get a lot
of chances to collide with each other at these
densities.

I would have figured that there is enough ambient background radiation
to keep it ionized.


- Randy

"Marvin" wrote in message
...
: Androcles wrote:
: http://antwrp.gsfc.nasa.gov/apod/ap071224.html
:
: Please read the caption.
:
: " Sprawling across hundreds of light-years, emission nebula IC 1396
mixes
: glowing cosmic gas and dark dust clouds. Stars are forming in this area,
: only about 3,000 light-years from Earth. This detailed view was created
in
: light primarily emitted by hydrogen gas, recorded through a filter that
: narrowly transmits a wavelength characteristic of glowing hydrogen atoms
in
: the nebula. "
:
: Now look at this:
: http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html
:
: "This spectrum was produced by exciting a glass tube of hydrogen gas
with
: about 5000 volts from a transformer. It was viewed through a diffraction
: grating with 600 lines/mm."
:
: Do the chemists agree with the astronomers that the hydrogen GAS is
atomic
: as opposed to molecular?
:
:
: Hydrogen atoms and molecules have different spectra, and
: they are the same for each regardless of whether the light
: comes from a discharge in a laboratory or from space. (But
: the Doppler shift must be taken into account when the light
: source is moving relative to the observer.) The list of
: wavelengths at the Web site you gave is what is emitted by
: hydrogen atoms. Chemists and physicists agree with this.

So molecules of hydrogen break their valency bonds and become
separated atoms when in vacuum, is that what you are saying?
Or are you merely attempting to obfuscate the issue by introducing
some imagined and totally irrelevant Doppler shift?

"Marvin" wrote in message
...
: Androcles wrote:
: http://antwrp.gsfc.nasa.gov/apod/ap071224.html
:
: Please read the caption.
:
: " Sprawling across hundreds of light-years, emission nebula IC 1396
mixes
: glowing cosmic gas and dark dust clouds. Stars are forming in this area,
: only about 3,000 light-years from Earth. This detailed view was created
in
: light primarily emitted by hydrogen gas, recorded through a filter that
: narrowly transmits a wavelength characteristic of glowing hydrogen atoms
in
: the nebula. "
:
: Now look at this:
: http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html
:
: "This spectrum was produced by exciting a glass tube of hydrogen gas
with
: about 5000 volts from a transformer. It was viewed through a diffraction
: grating with 600 lines/mm."
:
: Do the chemists agree with the astronomers that the hydrogen GAS is
atomic
: as opposed to molecular?
:
:
: Hydrogen atoms and molecules have different spectra, and
: they are the same for each regardless of whether the light
: comes from a discharge in a laboratory or from space. (But
: the Doppler shift must be taken into account when the light
: source is moving relative to the observer.) The list of
: wavelengths at the Web site you gave is what is emitted by
: hydrogen atoms. Chemists and physicists agree with this.

So molecules of hydrogen break their valency bonds and become
separated atoms when in vacuum, is that what you are saying?
Or are you merely attempting to obfuscate the issue by introducing
some imagined and totally irrelevant Doppler shift for something
that is hundreds of light years wide or is not moving in the
laboratory?

Never mind, I'll await an answer from some that actually is a chemist.
I didn't ask for a physicist's opinion, they are clueless anyway.

"Randy Poe" wrote in message
...
: On Jan 2, 12:25 pm, Marvin wrote:
: Androcles wrote:
: http://antwrp.gsfc.nasa.gov/apod/ap071224.html
:
: Please read the caption.
:
: " Sprawling across hundreds of light-years, emission nebula IC 1396
mixes
: glowing cosmic gas and dark dust clouds. Stars are forming in this
area,
: only about 3,000 light-years from Earth. This detailed view was
created in
: light primarily emitted by hydrogen gas, recorded through a filter
that
: narrowly transmits a wavelength characteristic of glowing hydrogen
atoms in
: the nebula. "
:
: Now look at this:
: http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html
:
: "This spectrum was produced by exciting a glass tube of hydrogen gas
with
: about 5000 volts from a transformer. It was viewed through a
diffraction
: grating with 600 lines/mm."
:
: Do the chemists agree with the astronomers that the hydrogen GAS is
atomic
: as opposed to molecular?
:
: Hydrogen atoms and molecules have different spectra, and
: they are the same for each regardless of whether the light
: comes from a discharge in a laboratory or from space. (But
: the Doppler shift must be taken into account when the light
: source is moving relative to the observer.) The list of
: wavelengths at the Web site you gave is what is emitted by
: hydrogen atoms. Chemists and physicists agree with this.
:
: If I were to hazard a guess
:
We all know that science to you is a hazardous guessing game, Poe.
Nobody is interested in your hazardous guesses.

On Jan 2, 5:52*pm, "Androcles" wrote:
"Marvin" wrote in message

...: Androcles wrote:

: * *http://antwrp.gsfc.nasa.gov/apod/ap071224.html
:
: Please read the caption.
:
: " Sprawling across hundreds of light-years, emission nebula IC 1396
mixes
: glowing cosmic gas and dark dust clouds. Stars are forming in this area,
: only about 3,000 light-years from Earth. This detailed view was created
in
: light primarily emitted by hydrogen gas, recorded through a filter that
: narrowly transmits a wavelength characteristic of glowing hydrogen atoms
in
: the nebula. "
:
: Now look at this:
: *http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html
:
: "This spectrum was produced by exciting a glass tube of hydrogen gas
with
: about 5000 volts from a transformer. It was viewed through a diffraction
: grating with 600 lines/mm."
:
: Do the chemists agree with the astronomers that the hydrogen GAS is
atomic
: as opposed to molecular?

At low pressures the most visible emission lines are those
characteristic of atomic hydrogen Balmer series.

: Hydrogen atoms and molecules have different spectra, and
: they are the same for each regardless of whether the light
: comes from a discharge in a laboratory or from space. *(But
: the Doppler shift must be taken into account when the light
: source is moving relative to the observer.) *The list of
: wavelengths at the Web site you gave is what is emitted by
: hydrogen atoms. Chemists and physicists agree with this.

So molecules of hydrogen break their valency bonds and become
separated atoms when in vacuum, is that what you are saying?

Molecular hydrogen is the most common molecule in the universe. But
still pretty rare. Hard UV will cleave it and with a huge mean free
path recombination events are rare. Hydrogen atoms are about 250x more
common still. See for example:

http://www.sciencedaily.com/releases...0508112217.htm

Molecular clouds near young UV bright stars are interesting places to
study exotic chemistry.

Regards,
Martin Brown

"Martin Brown" wrote in message
...
On Jan 2, 5:52 pm, "Androcles" wrote:
"Marvin" wrote in message

...: Androcles wrote:

: http://antwrp.gsfc.nasa.gov/apod/ap071224.html
:
: Please read the caption.
:
: " Sprawling across hundreds of light-years, emission nebula IC 1396
mixes
: glowing cosmic gas and dark dust clouds. Stars are forming in this
area,
: only about 3,000 light-years from Earth. This detailed view was
created
in
: light primarily emitted by hydrogen gas, recorded through a filter
that
: narrowly transmits a wavelength characteristic of glowing hydrogen
atoms
in
: the nebula. "
:
: Now look at this:
: http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html
:
: "This spectrum was produced by exciting a glass tube of hydrogen gas
with
: about 5000 volts from a transformer. It was viewed through a
diffraction
: grating with 600 lines/mm."
:
: Do the chemists agree with the astronomers that the hydrogen GAS is
atomic
: as opposed to molecular?

: At low pressures the most visible emission lines are those
: characteristic of atomic hydrogen Balmer series.

Assertion carries no weight, sorry.



: Hydrogen atoms and molecules have different spectra, and
: they are the same for each regardless of whether the light
: comes from a discharge in a laboratory or from space. (But
: the Doppler shift must be taken into account when the light
: source is moving relative to the observer.) The list of
: wavelengths at the Web site you gave is what is emitted by
: hydrogen atoms. Chemists and physicists agree with this.

So molecules of hydrogen break their valency bonds and become
separated atoms when in vacuum, is that what you are saying?

: Molecular hydrogen is the most common molecule in the universe. But
: still pretty rare. Hard UV will cleave it and with a huge mean free
: path recombination events are rare. Hydrogen atoms are about 250x more
: common still. See for example:

http://www.sciencedaily.com/releases...0508112217.htm

"an otherwise invisible galaxy that we observe when the Universe
was less than 1.5 billion years old"
Yeah, pull the other leg, it's got Big Ben on it. That kind of pop
science impresses me about the same as a hip hop rapper would
impress Beethoven with a Gregorian chant.


: Molecular clouds near young UV bright stars are interesting places to
: study exotic chemistry.


The Balmer series lies in the visible region yet you claim UV
is needed to split the molecule.
That would be the Lyman series with its shorter wavelength.

How do we know Balmer wasn't using molecular hydrogen in
his studies?
Sure, we can repeat them with a discharge tube, but its going
to be molecular hydrogen we put in it to start with. What evidence
do you have that it doesn't remain molecular and the Balmer
series is for molecular rather than atomic hydrogen?