Radioactivity/Decay

[Qester]

Is radioactivity/decay still tested on the MCAT? It is my TPR book but not my EK book (as far as I can tell) and I didn't see it on the AAMC topic list. anyone know for sure?

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[Dipraman]

Is radioactivity/decay still tested on the MCAT? It is my TPR book but not my EK book (as far as I can tell) and I didn't see it on the AAMC topic list. anyone know for sure?

They did talk about it in EK audio osmosis and I think there was a question one of the practice exams. I would just look over it to be safe. It's fairly easy and should't take you more than 10 mins

 

[Qester]

They did talk about it in EK audio osmosis and I think there was a question one of the practice exams. I would just look over it to be safe. It's fairly easy and should't take you more than 10 mins

As of right now I have it memorized and is not a problem but if I can save room in my brain for not having to know the different types of decay it would be sweet

 

[Jepstein30]

1) Go look up the official AAMC topic list. If it's on there, it's testable. Such a valuable resource that not many even notice.
2) Definitely still tested. Be comfortable with figuring out half-lifes as well as other applications.
3) Easy enough topic that you should spend the half hour reviewing it in case it does show up!

 

[Qester]

1) Go look up the official AAMC topic list. If it's on there, it's testable. Such a valuable resource that not many even notice.
2) Definitely still tested. Be comfortable with figuring out half-lifes as well as other applications.
3) Easy enough topic that you should spend the half hour reviewing it in case it does show up!

Thanks everyone for your help!

When I originally looked at the AAMC PS outline I had only looked at the Chemistry section since it was covered in my chemistry book, but I just found it in the physics section! Looks like I will keep it in my mind!

 

[Jepstein30]

Thanks everyone for your help!

When I originally looked at the AAMC PS outline I had only looked at the Chemistry section since it was covered in my chemistry book, but I just found it in the physics section! Looks like I will keep it in my mind!

Yea, I suggest printing those guys out and methodically checking each and every line off as you review it. Would suck to miss a line that ends up being featured in a passage on your test!

 

[Qester]

Yea, I suggest printing those guys out and methodically checking each and every line off as you review it. Would suck to miss a line that ends up being featured in a passage on your test!

Very true that's great advice, I actually do utilize those to determine what is relevant I was just having a hard time finding radioactive/decay on the topic list that's why I was asking if anyone else had found it there After seeing it in the physics section I am assuming my EK book will cover it there instead of the chemistry section (these prep companies need to get on the same page )

 

[mcgst9]

Very true that's great advice, I actually do utilize those to determine what is relevant I was just having a hard time finding radioactive/decay on the topic list that's why I was asking if anyone else had found it there After seeing it in the physics section I am assuming my EK book will cover it there instead of the chemistry section (these prep companies need to get on the same page )

It is definitely still on there. And it's the easiest thing in my opinion. I am typing it out to make sure I know it too!

Half life (T1/2) = 1/2 of material decays in that time. If T1/2 = 6 minutes, after six minutes a 5g sample will have become 2.5g.

Note that the total mass does NOT change, only the mass of your sample because when something decays, it changes to another element. So if you watched the previous thing decay on a scale, you wouldn't see any change, even though you obviously know you should have half as much in 6 minutes.

Know decay processes:

Alpha particle = 2 neutrons + 2 protons (helium nuclei) These are subtracted from the parent molecule. Mass decreases by 4, Z number decreases by 2.

Beta - decay = Neutron turns to proton, a negative charged particle is ejected from nucleus. Mass number does not change, Z number increases by 1.

Beta + decay (positron) = Proton becomes a neutron, positive particle (still an "electron") is ejected from nucleus. Mass does not change, Z number decreases by 1.

Electron capture = Proton turns into neutron from the nucleus combining proton and electron. Mass number does not change, Z number decreases by 1.

Gamma and x-ray radiation are not really a decay process but it can accompany them I believe. Note that gamma radiation comes from the nucleus, x-ray radiation comes from electrons (when they are excited and move back down to ground state). Mass and Z number stay the same.

And I think that's pretty much it other than the whole mass error thing that I am personally not too familiar with. I think you basically add up all the weights of each sub atomic particle and subtract from what it actually weighs. This is due to forces within the nucleus I believe.

 

[Qester]

It is definitely still on there. And it's the easiest thing in my opinion. I am typing it out to make sure I know it too!

Half life (T1/2) = 1/2 of material decays in that time. If T1/2 = 6 minutes, after six minutes a 5g sample will have become 2.5g.

Note that the total mass does NOT change, only the mass of your sample because when something decays, it changes to another element. So if you watched the previous thing decay on a scale, you wouldn't see any change, even though you obviously know you should have half as much in 6 minutes.

Know decay processes:

Alpha particle = 2 neutrons + 2 protons (helium nuclei) These are subtracted from the parent molecule. Mass decreases by 4, Z number decreases by 2.

Beta - decay = Neutron turns to proton, a negative charged particle is ejected from nucleus. Mass number does not change, Z number increases by 1.

Beta + decay (positron) = Proton becomes a neutron, positive particle (still an "electron") is ejected from nucleus. Mass does not change, Z number decreases by 1.

Electron capture = Proton turns into neutron from the nucleus combining proton and electron. Mass number does not change, Z number decreases by 1.

Gamma and x-ray radiation are not really a decay process but it can accompany them I believe. Note that gamma radiation comes from the nucleus, x-ray radiation comes from electrons (when they are excited and move back down to ground state). Mass and Z number stay the same.

And I think that's pretty much it other than the whole mass error thing that I am personally not too familiar with. I think you basically add up all the weights of each sub atomic particle and subtract from what it actually weighs. This is due to forces within the nucleus I believe.

Right, In my calculus class we covered half life substantially so I have no problem with that, I just get Beta + and Beta - confused I will just have to memorize

What you're talking about is nuclear binding energy I believe and it is calculating the mass deficit x c^2 to find the binding energy which per nucleon determines how stable the atom is.

But not to get sidetracked both of these are on the AAMC topic list.

 

[mcgst9]

Right, In my calculus class we covered half life substantially so I have no problem with that, I just get Beta + and Beta - confused I will just have to memorize

What you're talking about is nuclear binding energy I believe and it is calculating the mass deficit x c^2 to find the binding energy which per nucleon determines how stable the atom is.

But not to get sidetracked both of these are on the AAMC topic list.

Just think about the decay logically. If a negative charge is released from the nucleus, it MUST have come from a neutron, and it MUST cause a positive charge to be there.

If a positive charge leaves, them you must either end up with a negative or neutral charge in the nucleus, and you would never have a negative charge, so it must have come from a proton.

 

[gettheleadout]

Just think about the decay logically. If a negative charge is released from the nucleus, it MUST have come from a neutron, and it MUST cause a positive charge to be there.

If a positive charge leaves, them you must either end up with a negative or neutral charge in the nucleus, and you would never have a negative charge, so it must have come from a proton.