P4 Radioactivity Flashcards
Activity
the number of unstable atoms that decay per second in a radioactive source.
Alpha radiation
alpha particles, each composed of two protons and two neutrons, emitted by unstable nuclei.
Atomic number
the number of protons (which equals the number of electrons) in an atom. It is sometimes called the proton number.
Background radiation
ionising radiation that is around us all the time from a number of sources. Some background radiation is naturally occurring, but some comes from human activities.
Beta radiation
beta particles that are high energy electrons created in, and emitted from, unstable nuclei.
Control rod
a rod that can be lowered into the core of a nuclear reactor, to absorb neutrons and slow down the nuclear chain reaction.
Cosmic rays
charged particles with a high energy that come from stars, neutron stars, black holes and supernovae.
Count rate
Count rate: the number of counts per second detected by a Geiger counter
Decay
when a radioactive isotope emits ionising radiation
Decommission
Dismantle safely
Fuel rod
a rod containing the nuclear fuel for a nuclear reactor.
Gamma radiation
electromagnetic radiation emitted from unstable nuclei in radioactive substances.
Geiger Muller tube
a device that can detect ionising radiation and is used to measure the activity of a radioactive source.
Half life
average time taken for the number of nuclei of the isotope (or mass of the isotope) in a sample to half.
Ionisation
any process that in which atoms become charged.
Irradiated
an object has been exposed to ionising radiation.
Isotope
atoms with the same number of protons and different number of neutrons.
Mass number
the number of protons and neutrons in a nucleus.
Nuclear equation
an equation representing a change in an atomic nucleus due to radioactive decay. The atomic numbers and mass number must balance.
Random
any process that cannot be predicted and can happen at any time is said to be random.
Unstable
an unstable nucleus in an atom is one that will decay and give out ionising radiation.
When is light emitted from an atom?
When an electron falls down an energy level
What happens when an electromagnetic wave is absorbed by an atom?
An electron is promoted to a higher energy level
What is radioactivity?
Caused by nuclear changes. It is harmful and can cause burns or cancer. We are surrounded by it at a low level. Released by nuclear fuels.
What is an alpha particle?
Produced by alpha rays and alpha radiation. +2 charge
How far can alpha particles travel in air?
An inch
What can block alpha particles?
A sheet of paper
How ionising are alpha particles?
Highly