Radioactivity Flashcards
Nucleus
The very small and dense part of an atom, which contains protons and neutrons
Proton
A tiny positive particle found inside the nucleus of an atom
Neutron
A dense particle found in the nucleus of an atom. It is electrically neutral, carrying no charge
Electron
A tiny particle with a negative charge. Electrons orbit the nucleus in atoms or ions
Alpha radiation
Alpha particles, each composed of two protons and two neutrons, emitted by unstable nuclei
Gamma radiation
Electromagnetic radiation emitted from unstable nuclei in radioactive substances
Alpha (α) decay
The nucleus loses 2 protons and 2 neutrons, which are emitted as an α particle
Beta (ß) decay
A neutron in the nucleus changes into a proton and an electron - the electron is instantly emitted
Isotope
Isotopes of an element are atoms with the same number of protons but different numbers of neutrons. Therefore they have the same atomic number but different mass numbers
Ionisation
Any process in which atoms become charged
Tracers
A small amount of a radioactive substance used to give information about a mechanical or biological system
Radioactive dating
The use of a radioactive substance to give information about the age of an object
Carbon dating
A type of radioactive dating used to fine the age of organic materials
Uranium dating
A type of radioactive dating used to find the age of igneous rocks
What is a radioactive substance?
A radioactive substance contains unstable nuclei that become stable by emitting radiation
What types of radiation are given out from a radioactive substance?
Alpha, beta and gamma radiation
When does a radioactive source give out radiation?
Radioactive decay is a random event - we cannot predict or influence when it will happen
Where does background radiation come form?
Background radiation is from radioactive substances in the environment or from space or from devices such as X-ray machines
How was the nuclear model of the atom established?
Rutherford used the measurements from alpha-scattering experiments to prove that an atom has a small positively charged central nucleus where most of the mass of the atom is located
Why was the plum pudding model of the atom rejected?
The plum pudding model could not explain why some alpha particles were scattered through large angles
Why was the nuclear model accepted?
The nuclear model of the atom correctly explained why the alpha particles are scattered and why some are scattered through large angles
How does the nucleus of an atom change when it emits an alpha particle?
The nucleus loses 2 protons and 2 neutrons, which are emitted as an α particle
How does the nucleus of an atom change when it emits a beta particle?
A neutron in the nucleus changes into a proton, creating an electron which is instantly emitted
What are the properties of alpha radiation?
α radiation of stopped by paper, has a range of a few centimeters in air and consists of particles, each composed of two protons and two neutrons