Geiger tube

So a geiger tube works when ionising radiation enters and ionises the gas atoms along its track. The negative ions are attracted to the anode and positive ions are attarcted to the cathode etc etc.
But how can negative ions be created when ionising radiation removes electron(s) from atoms? Don't electrons need to be added, not removed to create anions? :s-smilie:

Reply 1

Kallisto

Entertainment Forum Helper

22

Original post by G.Y

So a geiger tube works when ionising radiation enters and ionises the gas atoms along its track. The negative ions are attracted to the anode and positive ions are attarcted to the cathode etc etc.
But how can negative ions be created when ionising radiation removes electron(s) from atoms? Don't electrons need to be added, not removed to create anions? :s-smilie:

The answer: Not at all. Positive ions are created when electrons remove. Those different charges would recombine immediately when the radiation is gone. By applying a potential, recombination is prevented and the charges are separated instead.

Reply 2

Joinedup

20

Original post by G.Y

So a geiger tube works when ionising radiation enters and ionises the gas atoms along its track. The negative ions are attracted to the anode and positive ions are attarcted to the cathode etc etc.
But how can negative ions be created when ionising radiation removes electron(s) from atoms? Don't electrons need to be added, not removed to create anions? :s-smilie:

I've never seen an explanation like that before... it's +ve ions and electrons... the electrons are being removed from the neutral atoms to leave the +ve ions.

the electrons accelerate rapidly towards the anode because they have a high charge to mass ratio - the ions are more sluggish because they have a far lower charge per mass.

there's a fair amount of fine tuning involved to get a GM tube that works properly

Reply 3

G.Y

OP

16

Original post by Kallisto

The answer: Not at all. Positive ions are created when electrons remove. Those different charges would recombine immediately when the radiation is gone. By applying a potential, recombination is prevented and the charges are separated instead.

So it's the elctrons removed from atoms to create cations that are attracted to the anode? And no actual anions are created at all?

Reply 4

Kallisto

Entertainment Forum Helper

22

Original post by G.Y

So it's the elctrons removed from atoms to create cations that are attracted to the anode? And no actual anions are created at all?

In general when electrons are removed from atoms, you have a lack of electrons in atoms, but a surplus of protons. Right? and a surplus of protons leads to positive charge, so positive ion. Those cations are attracted by the cathode, that is the box of the geiger tube.

Reply 5

Joinedup

20

Original post by G.Y

So it's the elctrons removed from atoms to create cations that are attracted to the anode? And no actual anions are created at all?

anions are attracted to anodes... so the anion itself is -ve charged
cations are attracted to cathodes... so the cation itself is +ve charged

http://www.bbc.co.uk/schools/gcsebitesize/science/triple_ocr_gateway/chemistry_out_there/electrolysis/revision/1/

in a GM tube you get cations... +ve charged ions which are attracted to the cathode
and free electrons (-ve charged of course) which are attracted to the anode

Geiger tube

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you