Destroyer'13 Q104 GC

[hope_to_match]

He gives mass and atomic number for Th (225, 90 respectively) and says that it undergoes 3 alpha decays, 4 beta decays and a gamma decay...

I got this question wrong because he never mentioned what kind of beta decay (beta emission or positron emission). When I looked at the solution he implied as though it was a positron emission and as a result the atomic number from 4 of those will increase by 4..

My question is: did anyone who take the DAT or did other practice problems have come across a GC problem on nuclear chemistry that does not specify the type of beta decay???

Thanks...

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[Xo1991]

Beta decay is beta decay. Positron emission is positron emission. Both are different

Beta particle have a -1 charge (adding a proton)

Positron emission has a +1 charge (lose a proton)

Both have a mass of 0.

 

[hope_to_match]

Beta decay is beta decay. Positron emission is positron emission. Both are different

Beta particle have a -1 charge (adding a proton)

Positron emission has a +1 charge (lose a proton)

Both have a mass of 0.

Chad's notes say Beta decay for both and then in parentheses he has B emission and Positron emission...

I am so confused...

I understand they are different...I was confused because both are Beta decay but there are two types of Beta decay one is B emission and the other Positron Emission. I know the difference between the two..I am confused because I thought it has to be specified whether it is a B emission or Positron Emission

 

[athomas]

When I looked at the solution he implied as though it was a positron emission and as a result the atomic number from 4 of those will increase by 4...

Super wrong, his answer implied beta decay not positron emission. The fact that the atomic number increased by 4 means two of our neutrons turned into protons

So we have a neutron here, let's say it's represented by =

Well, = is really just +- stuck together (for the sake of this example)

When we emit a positron +, what has our = become? It's now just a - . This would make our atomic number decrease by 1, not increase.

When we do beta decay and lose -, our = has become a + . This makes our atomic number increase by 1.

You may want to rewatch Chad's videos, because you are understanding it backwards.

 

[hope_to_match]

Super wrong, his answer implied beta decay not positron emission. The fact that the atomic number increased by 4 means two of our neutrons turned into protons

So we have a neutron here, let's say it's represented by =

Well, = is really just +- stuck together (for the sake of this example)

When we emit a positron +, what has our = become? It's now just a - . This would make our atomic number decrease by 1, not increase.

When we do beta decay and lose -, our = has become a + . This makes our atomic number increase by 1.

You may want to rewatch Chad's videos, because you are understanding it backwards.

i totally am..thanks