6) Radioactivity Flashcards
What is the mass of positrons?
The same mass as electrons
Who discovered the nucleus?
Rutherford
What did Rutherford conclude?
A positively charged mass in the centre of an atom repelled particles
What did Rutherford fire?
Alpha particles
What happens when atoms absorb EM radiation?
Electrons move to a higher energy level further from the nucleus
What happens when atoms emit EM radiation?
Electrons drop to a lower energy level closer to the nucleus
What is the proton number (Z)?
Total number of protons
What is the nucleon number (A)?
Total number of protons and neutrons
What are the isotopes of hydrogen?
Protium
Deuterium
Tritium
What are specific isotopes of an element called?
Nuclides
How does an unstable nucelus become more stable over time?
By randomly emitting ionising radiation
What is the process of randomly emitting ionising radiation called?
Radioactive decay
How often is decay?
Decay is spontaneous
What are the 3 types of ionising radiation?
Alpha
Beta
Gamma
When does gamma radiation happen?
When an excited nucleus releases energy
How is gamma radiation produced?
By gamma decay
What does a neutron decay to form in beta-minus decay?
A proton and electron
What does a proton decay to form in beta-plus decay?
A neutron and positron
What happens to the products of beta decay?
They are ejected from the nucleus
What does alpha radiation release?
Helium nuclei (alpha particles)
What does alpha radiation do to the mass of the nucleus?
Decreases by 4 atomic units (2 protons and 2 neutrons)
How can radioactivity be detected?
Photographic film
Geiger-Muller tube
Cloud chamber
How do photographic films show radiation?
A bright spot appears where ionising radiation hits the film
How does a cloud chamber show radiation?
A chamber full of alcohol vapour condenses on ionising radiation leaving a trail of radiation