* Nuclear fission - You can split the nucleus of an atom into two smaller fragments with a neutron. This method usually involves isotopes of uranium (uranium-235, uranium-233) or plutonium-239.
* Nuclear fusion -You can bring two smaller atoms, usually hydrogen or hydrogen isotopes (deuterium, tritium), together to form a larger one (helium or helium isotopes); this is how the sun produces energy
In either process, fission or fusion, large amounts of heat energy and radiation are given off.
To build an atomic bomb, you need:
* A source of fissionable or fusionable fuel
* A triggering device
* A way to allow the majority of fuel to fission or fuse before the explosion occurs (otherwise the bomb will fizzle out)
Before we talk about the physics of atomic bombs, it’s a good idea to go over the basic properties of atoms.
Atoms are incredibly small — the smallest is about 10-8 cm in diameter. For an idea of how small this really is, think of a baseball. The diameter of a baseball is about 7 cm. If an atom were the size of a baseball, an actual baseball would be about 3044 miles high.
An atom is made up of three subatomic particles — protons, neutrons and electrons. The center of an atom, called the nucleus, is composed of protons and neutrons. Protons are positively charged, neutrons have no charge at all and electrons are negatively charged. The proton-to-electron ratio is always one to one, so the atom as a whole has a neutral charge. For example, a carbon atom has six protons and six electrons.
An atom’s properties can change considerably based on how many of each particle it has:
* The number of protons in an atom determines the type of element. Elements are classified by their atomic number, which is simply the number of protons in an atom’s nucleus. Some common elements on Earth are oxygen, carbon and hydrogen. You can see the elements on the periodic table here.
* There are different types of atoms called isotopes. These isotopes look and act the same in nature — the only difference is the number of neutrons in the nucleus.
* You can calculate the “mass” of an atom by counting the number of protons and neutrons inside the nucleus. This number is called the atomic mass. Carbon has three isotopes, for example — carbon-12 (six protons + six neutrons), carbon-13 (six protons + seven neutrons) and carbon-14 (six protons + eight neutrons).