alpha particles charged? AAMC 10 #47.

[dougkaye]

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After reading BR series and EK also, I never got the impression that an alpha particle was charged. From EK: "An alpha particle is a helium nucleus. Thus, it contains 2 protons and 2 neutrons." I guess it follows that because it is only the nucleus, it doesn't have the electrons and is therefore "doubly ionized" w/ a +2 charge. Now I know, but the language was a bit unclear. I think whenever a particle/atom is being discussed, it should be clearly emphasized if it's not a neutral species. Now I know for the real MCAT!

 

[gschl1234]

That's why its usually designated He^2+.

 

[dougkaye]

That's why its usually designated He^2+.

Neither BR nor EK designate the alpha particle as ionized by its SYMBOL, only via its description. But hey that's the reason we're studying so much - so we know when we take that actual exam! I agree with you - on other websites I have seen alpha particles symbolized with a +2 charge.

 

[BerkReviewTeach]

Neither BR nor EK designate the alpha particle as ionized by its SYMBOL, only via its description. But hey that's the reason we're studying so much - so we know when we take that actual exam! I agree with you - on other websites I have seen alpha particles symbolized with a +2 charge.

I think the omission of the ion charge stems from a convention more than anything. Most nuclear equations in chemistry and physics textbooks disregard the overall charges. The top of page 120 (in BR) briefly mentions that nuclear processes involve ions, but it's generally ignored as the focus in nuclear studies is on the change in the nucleus (and not the orbitting electrons).

Upon reading your post, I went to the BR book planning to show you it was in there, but contrary to what I thought I recalled, you are completely right that it's only mentioned in passing. This should be mentioned more (or at least emphasized with an additional sentence or two in that paragraph). I distinctly recall a BR question that has an alpha particle deflecting when passing through an electric field, but it's in a handout and not the book. There are a few questions in the inclass exams that address the charge of an alpha particle and it's actions in an electric field, so maybe in the upcoming printing they'll rectify that.

Good catch Dougkaye. From all that I've read here in the Q and A section, you are doing really well and your are dang smart.