Atomic Physics

• Protons carry the positive charge in the nucleus.
• Neutrons are neutral
• Negatively charged electrons orbit the nucleus
• Protons and neutrons make up most of the mass of an atom (electrons are very light)
• Proton and neutrons together are known as nucleons
• Protons and electrons don't change in isotopes, only the neutrons
• One isotope is stable, the others are unstable
• Unstable isotopes go under radioactive decay, emitting radiation as they change from one element to another.
• Many natural substances are radioactive, but they are usually not very concentrated so they do not cause a problem
• If a radioactive substance gets inside of us, its radiation can harm us, this means that we are contaminated.
• If the radiation produced hits our bodies, we say we have received a dose of radiation, meaning we have been irratiated.
• We are exposed to low levels of radiation, known as background radiation.
• The air is radioactive, as it contains a gas called radon, which seeps up to the Earth's surface form uranium rocks underground
• The ground contains radioactive substances
• Our foods and drinks are slightly radioactive
• Radiation reached us from space in the form of cosmic rays. Some of this radiation comes from the Sun, some from further out in space.
• Most radiation from artificial sources comes from medical sources. This includes the use of x-rays and gamma rays inside the body and the use of radiation for destroying cancer cells
• Exposure to radiation can cause cancer.
• More lives are saved than lost due to the use of radiation
• In the past, bombs were detonated in the air or on land and contributed much more to the dose of radiation exposure
• Flying in an aircraft is high in the atmosphere, it is not a serious problem to the occasional fliers, but crew needs to get check ups
• Small amounts of radioactive substances escape from the nuclear industry
• Radioactive decay is a random process
• If you study a sample of radioactive material, you cannot predict when the next atom will decay
• Radiation is emitted by the nucleus of an atom, the nucleus is unstable and an unstable nucleus emits radiation in an attempt to become stable which is known as radioactive decay
• An alpha particle is made up of 2 neutrons (Helium)
• A beta particle is an electron, but not one that orbits the nucleus, it is in the nucleus and has a negative charge of 1.
• Mass of beta particle is less than the alpha
• A gamma ray is a form of electromagnetic radiation - think of it as a wave with a very short wavelength
• An alpha/beta particle is fast moving and the nucleus that has emitted it recoils and therefore both particles have kinetic energy
• Gamma rays transfer energy as electromagnetic radiation
• Alpha particles are the most easily absorbed, they can be absorbed by a thin sheet of paper , and they can travel only about 5 cm in the air before they are absorbed.
• Beta particles can travel easily through air and paper, but are stopped by a few centimeters of lead/metals
• Gamma radiation is the most penetrating and takes several centimeters of lead or several meters concrete to absorb most of the gamma radiation
• When radiation passes through air, it may interact with the air molecules knocking electrons from them, so that the air molecules become charged
• Alpha particles are the most ionizing and gamma are the least ionizing
• Radiation from radioactive active substances causes ionization of the materials that absorb it and it is often known as ionizing radiation.
• Radioactive actives sources should be stored in a contained that will absorb as much of the radiation as possible, an example would be lead as it is a strong absorber of all 3 types of radiation.
• An intense dose of radiation causes a lot ionization in a cell, which can kill it.
• When someone suffers radiation burns, the cells affected die as if they have been burnt