4: Atomic Structure Flashcards
Activity:
The rate at which an unstable nucleus decays.
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: (and how electrons can transition between them)
The stable states in which electrons are found in around a nucleus. 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.
Fission Products:
Fission produces two smaller nuclei, two or three neutrons and gamma rays. All these products are released with kinetic energy.
Gamma Ray:
Electromagnetic radiation emitted from a nucleus.
Geiger-Muller Tube:
A detector that measures the count-rate of a radioactive sample.
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.
Ions:
Atoms with a resultant charge due to the loss or gain of electrons.
Irradiation:
The process of an object being exposed to nuclear radiation. The object doesn’t become radioactive.
Isotopes:
Atoms with the same number of protons but different numbers of neutrons. The atomic number is the same, but the mass number is different.
Mass Number:
The number of protons and neutrons in an atom.
Negative Ions:
Atoms that gained electrons and so have a resultant negative charge.
Neutrons:
A neutrally charged constituent of the nucleus.
Nuclear Explosions:
Nuclear explosions in nuclear weapons are caused by an
uncontrolled chain reaction which results in vast quantities of energy being produced in a very small period of time.
Nuclear Fission:
The splitting of a large and unstable nucleus into two smaller and more stable nuclei to produce energy.
Nuclear Fusion:
The joining of two small, light nuclei to form a larger, heavier one and release energy.
Nucleus:
The positively charged centre of an atom, containing protons and neutrons.
Plum Pudding Model:
An old model of the atom that represented the atom as a ball of positive charge, with negative charges distributed throughout it.
Positive Ions:
Atoms that have lost electrons and so have a resultant positive charge.
Protons:
A positively charged constituent of the nucleus.
Radioactive Contamination:
The unwanted presence of radioactive atoms on other
materials. It is hazardous due to the decay of the contaminating atoms.
Radioactive Decay:
The random process involving unstable nuclei emitting radiation to
become more stable.
Sieverts:
The unit used for radiation dosage.
Spontaneous Fission:
Fission that occurs without the absorption of a neutron.
Spontaneous fission is rare and in most cases, fission is induced with a neutron.
