4 - Atomic Structure

• Alpha Particle: A positively charged particle consisting of two protons and two neutrons.
• Atomic Number: The number of protons found in an atom of a specific element.
• Each element has a different atomic number.
• Background Radiation: Radiation that is found in small quantities all around us and originates from natural sources such as rocks and cosmic rays, as well as from man-made sources such as nuclear weapons testing and accidents.
• Becquerel: The unit of radioactive activity.
• Beta Particle: A high speed electron that a nucleus emits when a neutron converts into a proton.
• Bohr Model: A model of the atom that suggested that electrons orbit the nucleus at set distances.
• Chain Reaction: The process of neutrons released by a fission reaction, being absorbed by another unstable, large nuclei, and inducing further fission.
• Count-Rate: The number of decays that a detector measures per second.
• Electrons: A negatively charged constituent of the atom, that are found in different energy levels, around the nucleus.
• Energy Levels: The stable states in which electrons are found in around a nucleus.
• The positively charged nucleus, which contains neutrons and protons, is surrounded by negatively charged electrons.
• The relative mass of a proton is 1 and its charge is +1.
• Electrons can transition to a higher energy level through the absorption of electromagnetic radiation and can transition to a lower energy level through the emission of electromagnetic radiation.
• The relative mass of a neutron is 0 and its charge is 0.
• Fission Products: Fission produces two smaller nuclei, two or three neutrons and gamma rays.
• All these products are released with kinetic energy.
• The typical radius of an atom is 1 × 10−10 metres and the radius of the nucleus is 10,000 times smaller.
• Gamma Ray: Electromagnetic radiation emitted from a nucleus.
• Most (nearly all) the mass of the atom is concentrated at the nucleus.
• Geiger-Muller Tube: A detector that measures the count-rate of a radioactive sample.
• Electrons lie at different distances from the nucleus (different energy levels) and the electron arrangements may change with the interaction with EM radiation.
• All atoms of the same element have the same number of protons.
• Half-Life: The time it takes for the number of unstable nuclei of an isotope in a sample to halve, or the time it takes for the initial count rate of a sample of the isotope to halve.
• Neutral atoms have the same number of electrons and protons.
• Ions: Atoms with a resultant charge due to the loss or gain of electrons.
• Isotopes are atoms of the same element, but with different masses, which have the same number of protons but different number of neutrons.
• Irradiation: The process of an object being exposed to nuclear radiation.
• The object doesn’t become radioactive.
• For example, Carbon-12, Carbon-13 and Carbon-14.
• Isotopes: Atoms with the same number of protons but different numbers of neutrons.
• X is the letter of their element, A is the mass number (number of neutrons and protons), Z is the proton number, N is the charge.
• Mass Number: The number of protons and neutrons in an atom.
• On a normal neutral atom, electrons equal protons, so the charge cancels out.
• Negative Ions: Atoms that gained electrons and so have a resultant negative charge.
• If there are more electrons than protons, then the atom has a negative charge.
• Neutrons: A neutrally charged constituent of the nucleus.
• And they both (along with the neutrons) have kinetic energy.
• Fusion would be a much more efficient way of producing energy compared to fission however no design has been produced that could accomplish positive net energy on earth.
• The sun is a natural fusion reactor.