Chemistry 101

[Mohit Pandey]

J.J thomson experiment for discovering cathode rays
Gases under normal pressure are bad conductors of electricity. But why they become good conductors when they are subjected to low pressure ?
Under low pressure, their atoms would be allowed more movement and therefore inter-molecular space would increase. So, how does it allows to current to flow? Please clear the concept of low pressure, if needed.

[UncleAl]

In hard vacuum electrons freely flow down a voltage gradient once overcoming the vacuum work potential of the cathode. Under low pressure a conductive neutral plasma does not rapidly quench (second order kinetics).

If you had vapor of a stable free radical, would that be electrically conductive?

[HydrogenBond]

OK. But I had asked why atomic mass, which is relative to mass of C-12 and mass number, which is found by counting the no.s of protons and neutrons, are so close?

I interpret this to mean why are protons and neutrons in roughly a one-to-one proportion, so the average atomic weight is close to this proportion? We do get a little C13, but this is not stable but decays. It often takes a solar event to make C13 from C12. If the sun suddenly stopped shining the mass of C would actually slowly go toward C12.

It appears the one neutron and one proton ratio within carbon is the most stable or at the lowest energy. What is interesting is hydrogen averages close to 1 AMU with one proton and zero neutrons. Tritium is at the other extreme with a 2 to 1 neutron to proton ratio. Everything else is in the middle, with 1 to 1 being the closest to the mass number. Hydrogen is the odd duck.

[Mohit Pandey]

In hard vacuum electrons freely flow down a voltage gradient once overcoming the vacuum work potential of the cathode. Under low pressure a conductive neutral plasma does not rapidly quench (second order kinetics).

If you had vapor of a stable free radical, would that be electrically conductive?

Sorry, uncleAl. I am not understanding your point, especially the red ones.

[modest]

Originally Posted by Mohit Pandey

OK. But I had asked why atomic mass, which is relative to mass of C-12 and mass number, which is found by counting the no.s of protons and neutrons, are so close?

The atomic mass is close to the nucleon number because nearly all of the mass of an atom is the protons and neutrons. Electrons don't have much mass by comparison. Since 1 amu is 1/12 C-12 this means the number of nucleons (protons plus neutrons) will come close to the atomic mass.

-modest

[christian_george]

I'd like to say that I am quite disappointed to a poll about the 10 greatest inventions in the planet for the past 2000 years. They should have included the microscope!

[Michaelangelica]

I know all true chemists will be horrified by this question as a chemical = a chemical =an organic chemical.

But-
I just purchased some cheep Blood and Bone for my garden ($1 a kilo)
But it says same scary things on the ingredients list for someone who wants to buy something that came from organic 'ground up cows' or whatever

EG
N (as blood bone and flesh) 5%
Phosphorus citrate soluble 3%
Phosphorus citrate insoluble 2%
Calcium as bone 10%
Calcium as rock phosphate 2%
Fine material (??) 60%
Coarse material (?) 40%

So am I getting "organic" ground up cow or not?

[modest]

Nothing there is “unnatural” or scary in any way. It isn’t all biological in origin as it lists rock phosphate which literally is rock high in phosphorous. This is normal - and it says "as" rock phosphate rather than "from" rock phosphate which should mean the phosphorous was not manufactured from the rock artificial-like.

However, this is not a complete list of ingredients. It’s more a breakdown of the main components of a fertilizer. For instance, this product probably doesn’t have the cadmium that an artificial fertilizer would have. While I would think this is certainly the case and a very good thing at that - it’s impossible to say this is the situation for sure from the list above because it isn’t a comprehensive list of ingredients.

Bottom line - nothing in that list jumps out as scary.

[Mercedes Benzene]

Yeah, I would have to agree with modest. There isn't anything extraordinary or "scary" about that list.
Can you provide any more details?

[Lwelson]

Hi any chance in giving me an understanding of how plastics are made? i have to do a presentation on 'plastic' and everything about it.
Many thanks
Luke