radioactivity Flashcards
What did Rutherford discover
Positive nucleus (protons and neutrons) surrounded by negative electrons in shells
Describe how Rutherford disproved plum pudding model
Firing alpha particles at gold foil. The
wide scattering pattern suggested the nucleus.
Describe how electrons can jump to a higher energy level (further from the nucleus)
Absorption of electromagnetic radiation
Alpha radiation α
-helium nuclei or loss of two protons and two neutrons
-highly ionising
-low penetration
-stopped by paper
-range in air 5 cm
Alpha equations
Atomic mass decrease by 4, atomic number decrease by 2
Beta radiation β
-electron formed when a neutron turns into a proton
-mid ionising ability
-mid penetration
-stopped by aluminium
-range in air 1 metre
Beta equations
Atomic mass no change atomic number increase by 1
Gamma radiation γ
-EMS wave
-low ionising ability
-high penetration
-stopped by several inches of lead or metres of concrete
-range in air unlimited
Describe background radiation
Low-level radiation
What is contamination?
The unwanted presence of materials containing radioactive atoms
on other materials. The object is radioactive as long as the contaminant is in contact with it.
Half-life
The amount of time it takes for the number of radioactive nuclei of the
isotope to halve
What halves every half-life
The number of atoms and count rate
What can be read of a half-life graph?
Half life
What is the half-life of carbon 14 used for?
To age living thing
Why is radiation harmful?
It’s ionising
What is ionising
The ability to knock electrons out of atoms
What can radiation do to humans?
Can cause mutations to DNA leading to cancer or can kill the cell
What radiation do smoke detectors use
Alpha radiation
What radiation do thickness monitors use?
Beta radiation
Medical uses of radiation
Explore internal organs, control or
destroy unwanted tissues
Gamma radiation can be used to __________
Kill cancer cells
Which radiation an be used as a tracer?
Beta or gamma because the half-life must be long enough to detect but not too long
Natural sources of background radiation
cosmic rays (12.5%) food and drink
(12.5%) rocks and buildings (12.5%) radon gas (50%)
Man-made sources of radiation
(12.5%) nuclear fallout from weapon
tests, nuclear disasters, and medical uses
