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A-level physics (particles) question!
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olivier_
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The proton number of uranium is 92 and the proton number of radon is 88. Which series of decays turns a uranium nucleus into a radon nucleus?
So this was a multiple choice question and the correct option was:
"alpha + beta minus + beta minus + alpha + alpha"
But I'm confused as to why this is correct, because to go from 92 to 88 you need to decrease by 4 not increase. Alpha is +2 and beta minus is -1 so wouldn't the decay equation give +2-1-1+2+2=+4 overall?
Or would the effect on the proton number of the uranium be the opposite in order to balance out the equation with the +4 so in fact the proton number is 92-4=88?
So this was a multiple choice question and the correct option was:
"alpha + beta minus + beta minus + alpha + alpha"
But I'm confused as to why this is correct, because to go from 92 to 88 you need to decrease by 4 not increase. Alpha is +2 and beta minus is -1 so wouldn't the decay equation give +2-1-1+2+2=+4 overall?
Or would the effect on the proton number of the uranium be the opposite in order to balance out the equation with the +4 so in fact the proton number is 92-4=88?
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Sinnoh
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You've got it the wrong way around. The uranium nucleus is losing nucleons in the alpha decay. Beta-minus decay increases atomic number.
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olivier_
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#3
(Original post by Sinnoh)
You've got it the wrong way around. The uranium nucleus is losing nucleons in the alpha decay. Beta-minus decay increases atomic number.
You've got it the wrong way around. The uranium nucleus is losing nucleons in the alpha decay. Beta-minus decay increases atomic number.
In my question I suggested two opposite ways of thinking about it, so which one did you mean is wrong??
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Sinnoh
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#4
(Original post by olivier_)
Alpha is +2 and beta minus is -1 so wouldn't the decay equation give +2-1-1+2+2=+4 overall?
Alpha is +2 and beta minus is -1 so wouldn't the decay equation give +2-1-1+2+2=+4 overall?
Or would the effect on the proton number of the uranium be the opposite in order to balance out the equation with the +4 so in fact the proton number is 92-4=88?
The nucleus loses an alpha particle's worth of nucleons in the decay. Yes an alpha particle has 2 protons and 2 neutrons, so an atomic number of +2, but this is being lost from the original nucleus, so you have to subtract it.
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olivier_
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#5
(Original post by Sinnoh)
This is wrong
This is correct
The nucleus loses an alpha particle's worth of nucleons in the decay. Yes an alpha particle has 2 protons and 2 neutrons, so an atomic number of +2, but this is being lost from the original nucleus, so you have to subtract it.
This is wrong
This is correct
The nucleus loses an alpha particle's worth of nucleons in the decay. Yes an alpha particle has 2 protons and 2 neutrons, so an atomic number of +2, but this is being lost from the original nucleus, so you have to subtract it.
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