Chapter 7 Radioactivity Flashcards
How was radioactive materials discovered
Henri becquerel used covered photographic plates that were placed under uranium salts to discover radioactivity.
Henri becquereles work was expanded on by marie & pierre curie, who investigated amd discovered a large range of new radio active elements.
What is radiation
The emmision of energy as electromagnetic waves or as moving subatomic particles
What are the main three different types of radiation
Beta,alpha,gamma
What is radioactivity
Process by which an unstable atomic nucleus looses energy by radiation
What occurs when an unstable nucleus decays
It emits radiation
What is background radiation
the natrual radiation that’s always present in the envriomment
3 sources of background radiation
Cosmic radiation,terrestial radiation,rocks and soil
What is a geiger counter
instruments that detect and measure ionizing radiation, as emitted by radioactive sources
What is the plum pudding model and who mad it in what year
After the discovery of the electron as being a subatomic particle in atoms, J. J.
Thomson came up with the Plum Pudding Model of the atom in 1904.
Electrons buried inside the atom which is made up of positively charged material
In the plum pudding:
What does the dough represent?
What does the plums represent?
How’s it different to todays model?
Cloud of positive charge
Electrons
Electrons inside nucelus whereas now they are in shells
3 observation and interprataions from rutherfords gold foil experiement
Most alpha particles traveled through the foil undeflected - Lot’s of empty space in an atom
Some alpha particles are deflected by small angles - As alpha particles are positvely charged it repelled the positvely charged nucleus
Occasionally, an alpha particle travels back from the foil - Alpha particles must have collided with someone dense in the centre,nucelus carrys most atomic mass in an atom
What is an isotope
An atom with a different number of neutrons
What is a radioisotope(example)
An isotope which is radioactive (carbon 14)
What is alpha radiation
The nucleus of a helium atom travelling at extremely high speed
Alpha decay math/equation
A X —— > A-4 D + 4 a
Z Z-2 2
What is beta radiation
The fast moving high energy electron not on an shell
Beta maths/equation
A X —— > A D + 0 B
Z Z+1 -1
What is gamma radiation
Part of EM spectrum; it’s a wave with very high freqeuncy a very short wavelength
Gamma maths/equation
Dosen’t change anything, needs alpha or beta with it to change
Fill in gaps- Radioactivity is measured in units of ________, where 1 unit is equal to one _________ per second.
Becquerels
Decay event
Fill in gaps - Nuclear radiation is the emission of ______ from the nucleus in the form of _______ particles or ___________ waves.
Energy,subatomic,electromagnetic
Fill in gaps - Unstable _______ decay ________ by the emission of _____, beta, or ______ radiation.
Nuclei,randomly,alpha,gamma
Alphas range in air,stopped by,ionsing ability
5cm
Piece of paper
Very strong ionising
Betas range in air,stopped by,ionsing ability
1m
Few mm of aluminium
Quite strong ionising
