* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Nuclear Chemistry Test Topics
Survey
Document related concepts
Hydrogen atom wikipedia , lookup
Elementary particle wikipedia , lookup
Effects of nuclear explosions wikipedia , lookup
Nuclear fusion wikipedia , lookup
Nuclear fission product wikipedia , lookup
Nuclear fission wikipedia , lookup
Chien-Shiung Wu wikipedia , lookup
Nuclear force wikipedia , lookup
History of subatomic physics wikipedia , lookup
Nuclear binding energy wikipedia , lookup
Nuclear structure wikipedia , lookup
Nuclear drip line wikipedia , lookup
Valley of stability wikipedia , lookup
Nuclear transmutation wikipedia , lookup
Atomic theory wikipedia , lookup
Transcript
Things To Know For The Nuclear Chemistry Test Transuranium elements are radioactive and produced by artificial transmutation and contain more than 92 protons. The element uranium is the largest element that occurs naturally. Transmutation occurs when one element is changed to another by changing the number of protons (atomic number). Artificial transmutation occurs in particle accelerators. Becquerel discovered that uranium gives off radiation by exposing photographic plates to uranium salts. Marie and Pierre Curie discovered polonium and radium. Enrico Fermi was the first to perform fission experiments. Radiation consists of particles and energy being given off by unstable nuclei. It cannot be seen or felt, but it is harmful to living things. An isotope of an element differs in the number of neutrons it contains. To determine the mass number of an atom, add the number of protons and the number of neutrons. When there are more protons than neutrons in a nucleus, the nucleus becomes unstable. The strong force cannot provide enough binding energy to hold the nucleus together, so the nucleus will undergo radioactive decay. The series of steps the nucleus undergoes to become a stable nucleus is called the decay series. Alpha particles are the weakest form of radiation and cannot penetrate a sheet of paper or clothing. The alpha particle is made up of a helium atom (2 protons and 2 neutrons). During alpha decay the unstable nucleus loses 2 protons which decreases the atomic number by 2. The unstable nucleus also loses 2 neutrons. The loss of 2 protons and 2 neutrons causes the mass number of the atom to decrease by 4. Beta particles are formed from the breakdown of a neutron into a proton and an electron. The electron is the beta particle and is ejected from the nucleus along with large amounts of energy. The gain of the proton from the breakdown of the neutron causes the atom’s atomic number to increase by 1 while its mass number remains the same. Gamma rays are electromagnetic waves that can penetrate several centimeters of lead. This is the strongest type of radiation. Remember, protons are positively charged and are attracted to negative charge while electrons are negatively charged and attracted to positive charge. HINT: Think about a magnetic field and how each type of radiation will react to that magnetic field. The half-life of a radioactive element is the fixed rate of decay. It is equal to the time required for ½ of the radioactive sample to decay to a stable state. Be able to perform half life calculations. Nuclear fission occurs when an unstable nucleus is bombarded by a neutron. This collision causes the nucleus to break apart and release large amounts of energy. The pieces of the broken nucleus bombard other unstable nuclei in the sample of material causing them to break apart. This chain of one nucleus splitting and causing others to split is called a chain reaction. At the end of fission stable nuclei will result and the energy released will be great! Uranium235 is commonly used in fission reactions. We use controlled fission to generate electricity in nuclear power plants. Nuclear fusion occurs when two smaller atoms are smashed together to form a larger atom. Nuclear fusion also generates large amounts of energy, but occurs at too high a temperature for man to use as an energy source. Fusion powers stars like our sun. Know your vocabulary! Know ways to detect radiation. Geiger counters are frequently used. Bubble chambers use a superheated liquid to detect radioactivity. Radioisotopes are used as chemical tracers because they have short half lives. They can be used to heat homes, detect chemical leaks, or be used in medical applications. Radioisotopes can be harmful, but their benefits sometimes outweigh the risks. Protons and neutrons are located in the nucleus of an atom while the electrons orbit outside the nucleus in specific areas called energy levels. The atomic number of an element tells how many protons are in the nucleus of that element. The mass number is equal to the atomic number plus the number of neutrons. Knowing this concept be able to calculate mass number, atomic number or the number of neutrons.