Nuclear energy comes directly from atoms. In most common processes, atoms of a heavy element such as uranium are split. Small amounts of matter in the atoms are converted to energy by the reaction. Large amounts of energy are release by atomic reactions. Electricity can be generated by this energy. .
All around the world, many places depend on nuclear energy for power. France actually gets 60 to 70 percent of its energy from nuclear power. There are about 500 nuclear power plants that in operation all over the world. The costs, safety, and waste disposal have put a doubt on the future of this energy.
About 20 percent of the total electricity generated in the United States accounts from nuclear power, and that can be equal to all the electricity in California, Texas and New York, which are the three most populated sates. In the year 2001 there were about 66 nuclear power plants throughout the U.S., and most were located on the East Coast and the Midwest.
Since all nuclear energy comes from atoms I"m going to explain how atoms come about. The basic properties of an atom are determined by the number of protons in its nucleus. All atoms of the same element have the same number of protons in their nuclei. The number of protons in an atom is called the atomic number of the element. Take oxygen for example, which has 8 protons, which means its atomic number is 8. For uranium, its atomic number is 92 which means it has 92 protons. The atoms of most elements have neutrons as well as protons and electrons. The numbers of protons and neutrons make up the atomic mass of an atom. The atomic mass unit (amu) is the unit of the mass for the atom. Take oxygen again, it has an atomic mass of 16. You can also figure out that oxygen has 8 neutrons because the atomic mass is equal to the number of protons and neutrons and you already know that oxygen has 8 protons.
Individual atoms of the same element may have different atomic masses.