p4 Flashcards
What is the radius of an atom?
1x10^-10 meters
What is an isotope?
same number of protons but different number of neutrons
What is the plump pudding model?
An early model of the atom by JJ thompson where the atom is a ball of positive charge with little balls of negative charge in it (electrons)
What does the atomic number give?
The number of protons
Who discovered the neutron?
In May 1932 James Chadwick announced that the core also contained a new uncharged particle
What is contamination?
Something becoming radioactive and staying radioactive even after leaving the source
What is irradiation?
Something being exposed to radiation and staying radioactive until it has left the source
What does ionising mean?
Removal of an electron from an atom?
What do we use to measure count rate?
A geiger counter
What type of radiation is the most penetrating?
Gamma rays
What is the definition of half life?
The time taken for radioactivity to fall half its original count
Why is radiation dangerous?
Can mutate cells, lead to cancer
What can we do to keep safe around radiation?
Keep as far away as possible, spend as little time near radioactive sources
What is the activity of a radioactive isotope measured in?
Becquerels (Bq)
What does the mass number give?
The number of protons and neutrons
How do we get the neutrons?
Minus the atomic number from the mass number
What is alpha, beta, gamma radiation made of?
Alpha - helium nucleus (2 protons, 2 electrons) Beta -1 fast moving electron, Gamma - electromagnetic wave
What is irradiation used for
Sterilising food/medical equipment
What was the experiment that disproved the plump pudding model?
The gold foil experiment
What was the gold foil experiment?
Shooting alpha particles at gold foil to see if any would bounce off, when a few did bounce off this disproved the plum pudding model
What are the three subatomic particles?
Protons and neutrons (inside nucleus) electrons (orbiting around the nucleus)
what type of radiation is the most ionising?
Alpha radition
What does ionising mean?
Removal of an electron from an atom
What happens to the mass number/atomic number during alpha decay
the mass number decreases by 4. the atomic number decreases by 2.
What happens to the mass number/atomic number during beta decay
Mass number remains the same, atomic number goes up by 1
What happens to the mass number/atomic number during gamma decay?
No change to atomic or mass number
