# What is the explosive power of 1 atom?

Most nuclear bombs contain large amounts of fusion material which I figure is required to create the chain reaction for a good explosion.

So what is the explosive rating of a signal atom (if we could split it without having to use special explosives that might mask the splitting of the atom)? I know the whole E=MC2 would the the energy released…so how does that translate to an explosive rating?

Would it be enough to blow up a car? a small building? a sky scraper?

A single atom? It wouldn’t be enough to blow up an amoeba. A single atom of uranium releases in the neighborhood of 200 MeV, which translates to roughly 0.00003204 joules.

Let’s take a single carbon atom. It has a mass of 1.92 x 10[sup]-26[/sup] kg.

Assuming the whole thing gets turned into energy, the energy released is:

E = mc[sup]2[/sup] = 1.92 x 10[sup]-26[/sup] (3 x 10[sup]8[/sup])[sup]2[/sup] = 1.73 x 10[sup]-9[/sup] J

That’s enough to light a 1 W lightbulb for about a nanosecond.

No it doesn’t. 200 MeV = 3.2 x 10[sup]-11[/sup] J.

That’s it? So this whole “splitting the atom” thing is just hype?
So then how much power is contained in a gram of matter? A kilogram?

Just how much uranium (or whatever modern nukes are made with) is in a nuclear bomb these days? I always figured it was just a few dozen Kg!

It is only a few kg. But there’s a LOT of atoms in one kg of uranium.

Quite right. For some reason I calculated 200 million MeV instead.

200 MeV (7.6 x 10[sup]-14[/sup] kcal) is about 5 billion times as much energy as is stored in a single carbon-carbon bond (90 kcal/mol -> 1.49x 10[sup]-22[/sup] kcal/bond). That’s not much energy in terms of lighting lightbulbs and such, but if its released in your liver, there’s enough punch to blow quite a few molecules apart.

How does one go about splitting an Atom?

In Science 30, This is brought up a few times for nuclear fission or fusion…or something, and as far as I can tell my crappy text book never says how.
I have a Diploma exam coming up next monday, and if I need to answer a written response about Nuclear reactions, I would like to know.

Depends on the atom. In the case of certain isotopes of uranium or plutonium, for instance, you shoot a neutron at it.

How do you do that? :rolleyes:

As it happens, those very same isotopes of uranium and plutonioum emit fast neutrons when they decay naturally. So, you just put a whole bunch of them in close proximity to one another, and the neutrons that fly out of the naturally-decaying nuclei hit intact atoms, causing them to decay, releasing more more neutrons, which, in turn, hit still more intact atoms…ad nauseum.

This is how an atomic bomb works. And when the reaction is controlled, nuclear reactors.

Thanks Q.E.D., but I still think I have studying to do though.

This site is chock full of nuclear goodness.

It sounds like you are underestimating how many atoms are in a kilogram. If I am correct (which sometimes happens), there are approximately 2.53x10^24 atoms in a kilogram of Uranium. Thats 2530000000000000000000000 atoms. Thats a lot. Even a little bit of energy multiplied that many times is a lot of energy.

(4.2 moles of U per kg, times avogadro’s number was my calculation)

And for hardcore physics, this site is pretty cool too – scroll to NWFAQ about two-thirds of the way down.

I am still getting used to the new forum software…
Avogadro’s number is used measure a mole of atoms. Carbon was the element of standard. 12 grams of carbon has avogadro’s number of carbon atoms 6.023e23.

The amount of fissile material to go critical (that is to have a decay event cause more than one decay event) depends on the amount of the fertile isotope and the shape. Uranium contains two isotopes 238 (nonfissile) and 235 (fissile). IIRC the 235 is on the order of 2.5% of bulk uranium and has to be separated from the bulk (this is the enriching process). Most uranium for fuel and bombs is enriched. For fuels the highest enrichment that I know is for submarines – maybe 80% enrichment.

In fission the uranium or plutonium will break down into two or more other atoms. The mass difference between the U/Pu and the products is used for the e=mc^2.

If there are errors, I apolgize in advance. I took my Nuclear Engineering class 20-some years ago.

Back to the OP. For those of us who cannot calculate the number of atoms per gram of fissile material.

If it were possible to split a single atom, say a plutonium isotope, would the reaction be visible? What if it occured in a cloud chamber?

What would we SEE? if anything?

In a cloud chamber? Yes

Also in certain rocks/crystals such as mica.

What is a MeV an abbreviation of?