What Is Radioactivity? Flashcards
What causes radioactivity to decrease?
Time
What does nuclear radiation do to materials?
It ionises materials
Where does the radiation of an atom come from?
The nucleus
Describe radioactive substances
They decay naturally and give out radiation in the form of alpha, beta and gamma
Explain half-life
It is the time it takes for half the undecayed nuclei in a radioactive substance to decay.
Explain ionisation
- removal or electrons from particles
- gain of electrons by particles
Explain why alpha particles are such good ionisers
Because they are relatively massive so they hit atoms hard enough to strip off electrons
What is an alpha particle?
A helium nucleus
What is a beta particle?
A fast moving electron
Describe what happens to a nucleus when an alpha particle is emitted
- mass number decreases by 4
- nucleus has two fewer electrons
- nucleus has two fewer protons
- atomic number decreases by 2
- new element formed
Describe what happens to a nucleus when a beta particle is emitted
- mass number is unchanged
- nucleus has one less neutron
- nucleus has one more proton
- atomic number increases by one
- new element formed
What is the radioactivity ir activity of an object measured by
The number of nuclear decays emitted per second
