P4-atomic Structure Flashcards
What model did J.J. Thomson create
The plum pudding model
What scientist proved that the plum pudding model was wrong and what was the experiment called
Rutherford proved the plum pudding model wrong by the alpha scattering experiment
What model did Rutherford make
Nuclear model
What scientist refined Rutherfords nuclear model
Niels Bohr
What are isotopes
Have the same number of protons
Different number of neutrons
What are the characteristics of alpha particles
Helium nucleus-2 protons/neutrons
Strongly ionising
Don’t penetrate far
Absorbed by a sheet of paper
Few cm in air
What are the characteristics of beta particles
High-speed electrons
Moderately ionising
Penetrate moderately
Absorbed by sheet of aluminium
Neutron turns into a proton
Few meters in air
What are the characteristics of gamma rays
EM waves
Long distance in air
Penetrate far into materials
Weakly ionising
Absorbed by thick sheets of lead or metres of concrete
In an alpha decay what happens to the charge and mass in the nucleus
Decreases
What can an alpha particle be written as
Helium nucleus
HE - 4 at the top - 2 at the bottom
What does beta decay do to the charge of the nucleus
Increases
What can beta decay be written as
e - 0 at the top , -1 at the bottom
What is half-life
The half-life is the time taken for the number of radioactive nuclei in an isotope to halve
How is radiation measured
GM tube
What are the risks to using radiation
Can enter living cells and ionise atoms within them
Can damage the cells, which could cause cancer or kill them off completely
What is irradiation
Exposure to radiation
What is contamination
Radioactive particles getting onto objects
What could be used when handling objects that are contaminated
Gloves
Tongs
Protective suits
What can be used when handling objects that are irradiated
Lead-lined boxes
Standing behind Barriers
Being in a different room
Where are gamma and beta sources the most dangerous and why
Outside the body
Can penetrate the body and get to delicate organs
Where are alpha sources the most dangerous and why
Inside the body
They do all their damage in a very localised area
How many times bigger is the radius of a helium atom than the radius of an alpha particle
More than 10 000 times bigger
What happens to an atom when it is ionised by an alpha particle
The atom becomes a positive ion
The atom loses an electron
Suggest why a park detector cannot detect beta radiation
Beta radiation is weakly ionising
