The atomic bomb

We did a whole unit on Nuclear Energy a few years ago. It was one of our favorite units! You can find all the posts about that unit aggregated here.

The Nuclear Museum in Albuquerque.

Hydrogen bombs vs. atom bombs

Great article on why we dropped the atomic bomb. And some more good resources on the same subject. Definitely worth watching and teaching. I found a real lack of good information on this subject elsewhere, as most children's books and other modern resources have a sort of glib "we all know better now" sensibility on the subject.

Abe and I LOVED this book, Bomb, by one of our favorite authors, Steve Sheinkin. There is SO MUCH intrigue and so many behind-the-scenes details I had never before heard about. It reads like a mystery novel.

I can also recommend this book (for adults and older children), Hiroshima Diary, which is a journal written by a doctor in Hiroshima in the weeks immediately following the Hiroshima bomb. It is fascinating, sad, and surprisingly good-humored as well. The author seems like a pretty amazing man.

Static Electricity and Ions

We started this unit with static electricity, and to understand that, you first have to understand ions. We learned about ions when we studied nuclear energy, but it was good for us to review it. (I think I finally have it down now, but I tend to get ions and isotopes mixed up, so a reminder is always helpful for me.) We made little diagrams using fwuffballs to represent the subatomic particles. We showed how an atom losing an electron could create charged particles, either positive or negative.

There are lots of fun things you can do with static electricity and a balloon. There's picking up tiny bits of paper, of course . . .

Or making a stream of water bend

Or sorting salt and pepper (if you get the balloon just the right distance away, the lighter pepper jumps up to the balloon while the heavier salt remains on the plate).

You can repel a piece of tape with another (rubbed) piece of tape

But maybe our favorite thing is just making people's hair stand up!

Also, here's a nice video of a lightning strike.

And here is a fun video showing how to light up a fluorescent bulb with static electricity.

Nuclear Fusion

So many of our books couldn't get over the idea that Fusion! is the Energy! of the Future!  I found their reasoning pretty simplistic and I'm not so convinced (nor am I sure the massive expenditures will pay off), but, regardless, it sure is interesting to learn about! I found what I think is the best activity EVER to demonstrate fusion. It's described here, but basically, when you apply heat and pressure to mini-marshmallows, they will "fuse" together. It's like magic! We loved it.

It's also helpful to show a chart of electromagnetic energy when you talk about the energy fusion releases; this is from here

We had our periodic tables handy, and we would choose two elements and get marshmallows to represent the number of protons in each one. For the simplest example, you take two atoms of hydrogen (one proton each; so you take one marshmallow in each hand)---add heat and pressure (roll them together between your palms very fast)---and they fuse to form a new element, Helium (2 protons)! At the same time they release lots of energy (represented by the lentils).

This happens at very high temperatures, in a plasma in fact, so the electrons are free and we don't even have to worry about them. :) If you really rub your hands together hard, the marshmallows fuse so completely, they look like one marshmallow again! Which is cool, but it's more helpful to see the individual "protons," so we backed off and didn't rub so hard. Still: magic!

I let the children create as many elements through fusion as they wished, as long as they told me which elements they started with, and their atomic numbers, and then figured out which new elements they were creating (also based on atomic number). They had so much fun, and the fused nuclei were truly amazing. They gained a lot of familiarity with the periodic table as well.

As we learned more about fusion we became curious about the transuranic elements: that is, the elements PAST Uranium on the Periodic Table that are man-made. How did they make them? None of our books seemed to mention this; they just said they were man-made and didn't occur naturally.

So, we asked Karl (my brother the physicist). Here's what we learned.

(our questions in black; Karl's answers in blue):

Now we have another question: how do they create the transuranic elements, and why is it not fusion when they do so? We read that they can be made in particle accelerators, but we thought that's what what's-her-name--Lise Meitner---was TRYING to do when she discovered fission. And she discovered that bombarding the nuclei DIDN'T add particles, but split the nucleus instead. I know some things are more fissionable (?) than others, like U-235, but they were using U-238 in those original experiments and that still split instead of adding protons.

Fission happens because very few configurations of protons/neutrons are stable.  When you send two nuclei together, they will most likely create an unstable nucleus which will then split into two more-stable elements, not necessarily the two that collided in the first place.  You might get lucky and find that one of the resulting elements is more massive than either target.  

And, even if they do have a way of making the protons "stick" and add themselves to the nucleus, why doesn't that create tons of energy like fusion? And if they can hardly even make Hydrogens fuse, how on earth could they make heavier elements fuse---which seems like it would be harder? 

To get excess energy from fusion, you need to have the mass of the combined nucleus be less that the mass of the separate nuclei by more than the amount of energy it takes to shove them together.  Larger nuclei are harder to shove together, and the mass difference is smaller, so no excess energy.  Yes, they are very hard to get to fuse, it takes huge accelerators.  Think of trying to push the N poles of two magnets together vs. trying to push 100 magnets together. 

The problem with H fusion (Deuterium, actually), is not getting them to fuse (they do it all the time).  The problem is getting it to be self-sustaining and not energy-consuming.  I just read an article by a high school science teacher claiming he had calculated that even D fusion could never be a net energy producer.  I was skeptical given that thousands of scientists clearly think it can be.  (But you might say they have a conflict of interest because they want funding.)  Hmmm. 

I bet it will take 100 years of a fusion generator to make back all the energy spent on fusion so far. 

Karl.

Interesting, eh?

The Atomic Bomb and WWII

My explanation of the famous equation. That's what it all comes down to, right? Anything x Very Big = also Very Big? :)

Every single day of this unit, the boys were saying, "Is TODAY the atomic bomb? Is TODAY the atomic bomb?" Finally we got to it. Having lived in Los Alamos while my dad worked at the lab there, I've always had a special interest in the Manhattan Project and the people who worked on it. My mom has lots of good books on the subject from our time in Los Alamos---just the portraits of their daily lives there (even the wives and children who were there with their physicist husbands) are really fascinating. I have pictures of me at the Trinity site when I was 3, but I don't remember it. I think I have some trinitite too. (I used to think my Uncle Hale worked on the Manhattan Project, but he didn't. He helped develop Radar, though.)

Anyway, I don't know what's more interesting, the history or the science! We had a unit on the Holocaust earlier this year, but we didn't cover the war with Japan at all, so we needed a brief recap of the timeline of World War II and an overview of Pearl Harbor, etc. This site has some interesting before and after pictures of Hiroshima and Nagasaki (before and after the bombs were dropped). I wouldn't get too far into this page with kids as there are some very disturbing pictures of people and their injuries; we stayed away from those. (They are behind a link at the bottom of the page, though, so you shouldn't run into them by accident.) Whatever your feelings on the bomb (another reason I wouldn't get too far into that site), it's very sobering to see the pictures and think about the destruction caused. 

I liked the story of Lise Meitner, one of the discoverers of fission and a very interesting woman. I've always liked Marie Curie but I'd never even heard of Lise Meitner before. There's an element named after her now (Meitnerium)! (I liked this whole book, though it wasn't all pertinent to this unit: serendipitous discoveries are so cool!)

Of course we also listened to Manhattan Project, one of the best Rush songs ever. :) This one made a deep impression on me as a teenager and I've liked it ever since.

There are videos all over online that show atomic bomb explosions. The boys loved those. They are pretty awe-inspiring! This video was one of the most interesting, about the largest thermonuclear bomb ever detonated.

Paper plate atom models

I thought of various ways we could build models of the atom, and finally decided on this one as the simplest. I saw some instructions for doing this with M&Ms, but as you were supposed to be gluing them to the plate, this promised to be either wasteful or futile. So we used beads. The main point of making a model, in my mind, was to cement the concept of which subatomic particles go where, and which ones determine the properties of an element---and this accomplishes that sufficiently.

I told the children they could choose any element to model. I helped Malachi and Daisy, of course (it was a good counting exercise for both of them---Malachi chose Gold, so he had to go up to 118 for the neutrons) and Abe and Seb were able to do this on their own.

Here's a simple, printable periodic table if you need one. I remember when I was in 6th or 7th grade, my dad brought home a periodic table for me that was colored and detailed (with the full mass numbers and such), printed on heavy paper. I was so proud of it and felt like I was SO lucky compared to everyone else in class that had to make do with their ugly Xerox copies. I kept it in my binder for years and always felt special when I brought it out during classes. It was such a simple little thing, I'm not sure why I loved it so much, but I think I just loved that my dad gave it to me. Anyway! This one isn't as nice, but it will do. :)

Abe wanted to do the lightest and the heaviest naturally-occurring elements.

Sebby wanted his to be shaped "right" :)

Isotopes (or, as we called them, eggotopes)

Regular Hydrogen with its isotopes, deuterium and tritium

I've always thought isotopes were a little tricky to visualize. But the concept is critical to understanding radioactivity and the uranium enrichment process! Luckily I found this great idea from a junior high science teacher online. You use colored eggs to represent elements. Each isotope of an element is in the same color. Inside, you make a nucleus with beads, showing the number of protons and neutrons in each isotope. The model leaves out electrons altogether, as they aren't relevant here.

(One thing the children were SO interested in was half-life---specifically, how some elements have such a short half-life that they decay almost immediately. Protactinium, for example, would have been totally gone from the earth only hours after it first appeared. They loved that idea, for some reason.)

We really liked doing this, and we also used the eggs later on in the unit for reference. I had really small plastic eggs, so we only did some of the lighter elements, but it would have been fun to make an egg for U-235 and U-238 if we'd had one big enough to hold that many beads! I just looked up a list of common isotopes (some radioactive, some not) such as Carbon-14 and of course the three isotopes of Hydrogen. (That knowledge would be necessary for learning about nuclear fusion later!)

Here's a simple online explanation of isotopes.

Also, stringing beads is fun!

Sulfur-32 and Sulfur-35 (radioactive)

Nuclear Energy Unit Lesson Plan

We decided to plan a nuclear energy unit after we went to the Museum of Nuclear Science and History in Albuquerque a few months ago. There was so much information at the museum, and the children were curious about it all, but there was too much to really absorb in a few hours. They asked if we could study it in more depth later, and I said we could, though I wasn't really sure how it would go. I wondered if the subject was maybe too complicated for me to cover (as, alas, I'm not a physicist. If only Grandpa were still alive!). But, I forged ahead and checked out a bunch of books from the library about atoms and nuclear energy.

Luckily (as seems to happen every time!), after reading so many books and trying to absorb so many explanations, everything began to make sense and I felt like I would actually be able to teach it! Not on a college level or anything, but well enough. I have wondered if this is perhaps the only post on "Nuclear Energy Homeschool Unit for Children" in the entire world! I certainly couldn't find anything no matter how much I searched online. However, there were some good resources on the individual sections of the unit---some for older students that I could adapt for a younger audience, and some that were a bit advanced but I thought we'd try anyway. The children loved our studies about hydropower, so I knew they'd be able to understand the basic model of a nuclear power plant once we had a good basic understanding of atomic structure and radioactivity.

Okay, that meant starting with atoms. We learned some about atoms and elements in our fireworks unit, so this wasn't totally new. One activity we did was to help answer this question: how do we learn anything about atoms if we can't even see them? I gave each of the children a paper bag, stapled shut, with something inside. They had to figure out what was in there without opening the bag. They could shake their bags, throw them, crumple them, feel them, etc. to determine what was inside. They did pretty well (though only Abe actually guessed his object correctly, I think) and I think it did a good job of conveying how, by doing things to atoms, we can learn about their properties even when we don't see them.

Another thing we did that ended up being really memorable was a demonstration of just how much empty space is inside an atom! I read in one of our books that if the nucleus was the size of a golf ball, the electrons would be rotating around it about 2 miles away! I showed the children the way we usually draw atoms (the nucleus with electrons hovering nearby) and then explained how it was just a convenient representation, but didn't show the actual scale of an atom. I put a golf ball on the table and asked them, "If the protons and neutrons are here, where would the electrons be?" We then got in the car, started the odometer, and drove until we'd gone two miles. Then I stopped the car, told them to remember where the nucleus was, and said, "The electrons would be clear out here!" They were amazed. :)

I usually put up butcher paper on the windows or walls as a place I can draw examples when we're learning about something. These are some of the terms we learned about as we reviewed atomic mass, atomic number, how to read a periodic table, what ions are, etc. We also talked about the four forces in the universe and their relative strengths and influences. All this was good background for what was to come.