Nuclear and Space Physics Definitions Flashcards
Alpha particle
A positively charged particle consisting of two protons and two neutrons. They are highly ionising but can be stopped by a few centimetres of air.
Atom
The smallest component of an element having the chemical properties of the element
Electrons
A negatively charged constituent of the atom
Ion
An atom which has lost or gained electrons to obtain an overall charge.
Neutron
A neutral particle in the nucleus of an atom. Their quantity varies between isotopes of the same element and can be found by subtracting the proton number from the nucleon number.
Nuclear model
The model developed from Rutherford’s alpha particle experiment
Proton
A positively charged particle in the nucleus of an atom. There are the same number of protons as electrons in a neutral atom
Isotope
Atoms with the same number of protons but different numbers of neutrons. The atomic number is the same
Nucleon number
The number of protons and neutrons in an atom.
Nucleus
A collection of particles called protons
Nuclide
Refers to an atom with a distinct number of protons and neutrons in its nucleus.
Nuclide notation
A shorthand method of showing information about atoms.
Proton number
The number of protons found in an atom of a specific element. Each element has a different proton number.
Background radiation
Radiation that is found in small quantities all around us.
Corrected count rate
The background radiation count produced solely from the source being investigated. Found by subtracting the count when the source is not present from the count when it is.
Count rate
The number of counts of radiation per second (units = Bq) or per minute.
Ionising radiation
Radiation capable of removing electrons from atoms
Radioactivity
When unstable atoms give radiation that can be harmful to humans.
Radiation
The energy emitted as electromagnetic waves or as moving subatomic particles (alpha
Beta particle
A high-speed electron that a nucleus emits when a neutron converts into a proton. They are ionising but can be stopped by a thin sheet of aluminium.
Gamma ray
Electromagnetic radiation emitted from a nucleus. They have a very high penetrating power and can penetrate up to several centimetres of lead.
Random nature of radioactive decay
You cannot predict which nuclei in a radioactive sample will decay next
Radioactive decay
The random process of unstable nuclei emitting radiation to become more stable. During α- or β-decay the nucleus changes to that of a different element.
Half-life
The time it takes for the initial count rate of a sample of an isotope to halve (different for different isotopes).
