Radioactivety Flashcards
(25 cards)
What is the structure of an atom?
A small nucleus of protons and neutrons, surrounded by electrons.
Where is most of the atom’s mass located?
In the nucleus.
What are isotopes?
Atoms of the same element with different numbers of neutrons.
What are the charges and masses of protons, neutrons, and electrons?
Proton: +1, 1
Neutron: 0, 1
Electron: -1, almost 0
Why is an atom neutral?
It has equal numbers of protons and electrons.
What happens when electrons absorb energy?
They move to a higher orbit.
How do atoms become positive ions?
By losing outer electrons.
What is radioactivity?
The spontaneous emission of particles or radiation from unstable nuclei.
What types of radiation are emitted by unstable nuclei?
Alpha, beta minus, beta plus, gamma
What is background radiation?
Radiation from natural and artificial sources always present in the environment.
What are the main sources of background radiation?
Rocks, cosmic rays, medical uses, nuclear industry.
How is radioactivity detected?
Using photographic film or a Geiger–Müller tube.
What is an alpha particle?
A helium nucleus (2 protons, 2 neutrons).
What is a beta particle?
An electron emitted from the nucleus during beta decay.
What is a gamma ray?
High-energy electromagnetic radiation.
Compare penetration of alpha, beta, and gamma.
Alpha is least, beta is medium, gamma is most penetrating.
How did Rutherford’s experiment change the atomic model?
It led to the nuclear model, replacing the plum pudding model.
What happens during beta minus decay?
A neutron becomes a proton and emits an electron.
What happens during beta plus decay?
A proton becomes a neutron and emits a positron.
What is the effect of alpha decay on atomic and mass number?
Atomic number decreases by 2, mass number by 4.
What is the half-life of a radioactive isotope?
The time taken for half the radioactive nuclei to decay.
What is the unit of activity?
The Becquerel (Bq).
What is irradiation?
Exposure to radiation without becoming radioactive.
What is contamination?
Unwanted presence of radioactive material on surfaces or inside the body.
