Radioactivity Flashcards
Who investigated the radiation of uranium salts
Henri Becquerel
Radioactivity is defined as
The spontaneous random decay of an unstable nucleus emitting alpha, beta or gamma particles
Who won the Nobel prize for physics
Pierre and Marie Curie
What did Pierre and Marie Cuire discover
The radioactive elements, polonium and radium
Describe alpha particles and give an application
2protons 2neutrons
Double positive charge
Relativity large mass
Slowest out of the types
Low penetrating power, not dangerous (piece of paper)
Attracted towards a negative plate
Americium 241- smoke detector
Describe Beta particles and give an application
They are electrons
Negative charge
Low mass
Travel quickly
High penetrating power (5mm Aluminium)
Attracted to a positive plate in a magnetic field
Carbon-14 used in carbon dating
Describe Gamma radiation and give an application
Electromagnetic radiation
No charged particles
No mass
High penetrating ability ( thick lead)
Not effected by electric fields
Cobalt 60 used in radiotherapy
What is used to detect radioactivity
A Geiger - Muller tube is used to detect radioactivity
What happens in Alpha nuclear reactions?
Atomic number- goes down by two
Mass number- goes down by four
What happens in Beta nuclear reactions?
Atomic number- goes up by one
Mass number- doesn’t change
What is transmutation
The changing of one element into a another
What is the half life on a element, is it affected by anything external ?
The time taken for half of the nuclei to decay
(External factors don’t affect the half life of a element)
What is a radioisotope
A radioactive isotope
Radioisotope uses
Smoke alarms: Americium 241-alpha
Carbon dating : Carbon 14- beta
Radiotherapy: Cobalt 60- Gamma
Explain Carbon Dating
The ratio is C-12 to C-14 in living things is constant. Although C-14 decays by beta radiation it’s continuously replaced while the organism is alive.
When an organism dies no more C-14 is taken in but the amount of the stable C-12 isotope remains the same.
By measuring the ratio of C-14 to C-12 in the remains of material scientists can work out the age of the items.
