TOPIC 4//Atomic Structure Flashcards
What are isotopes
Atoms of same elements which have same number of protons and but different number of neutrons
What is radioactive decay
When other unstable isotopes tend to decay into other elements and emit radiation as they try become more stable
Define radioactive
Unstable elements that can decay
What do Radioactive substances do
They spit out one or more types of ionising radiation from their nucleus and release neutrons when they decay to reduce their mass and turn into energy
What is ionising radiation
It is a radiation emitted from unstable nuclei that knocks off electrons from atoms creating positive ions
What does Radioactive substances do when they decay
Release neutrons
What are Alpha particles
Helium nuclei
An a-particle is 2 neutrons and 2 protons.
What is 4 facts about an Alpha Radiation
- alpha particle is emitted from the nucleus.
- They dont penetrate very far into materials and are stopped quickly.
- Because of their size they are strongly ionising.
- Absorbed by a sheet of paper
Why is Alpha radiation used in smoke detectors
It ionises air particles causing a current to flow
What are Beta Particles
High speed electrons released by the nucleus
Beta particles have virtually no mass and a charge of -1
What are 4 facts about Beta Radiation
- Moderately ionising
- They penetrate moderately far into materials before colliding because they have small mass and high speed
- Every beta particle emitted, a neutron in the nucleus decays into a proton and a electron.
- Absorbed by a sheet of metal/aluminium
Why are Beta particles/Emitters used to test the thickness of sheets of metal
As the particles are not immediately absorbed by the material and do not penetrate far into materials
What are Gamma Rays
EM waves with a short wavelength
What are 3 facts about Gama rays
- They penetrate far into materials without being stopped and will travel long distance through air
- Weakly ionising because they tend to pass through rather than collide with atoms
- Absorbed by lead/concrete
What does nuclear equations show
shows us what is produced when a radioactive nucleus decays
Nuclear equation for Beta decay
Atomic number increase by 1 and Mass number stays the same
Nuclear equation for Alpha decay
atomic number reduces by 2 and mass number reduce by 4
What do radioactive substances give out
Give out radioactive substances from nuclei of their atoms
How can radiation be measured per second
Geiger Muller tube and counter
What is meant by Radioactive decay
When a unstable nuclei loses energy by radiation ( Radioactive decay is completely random )
Define half life
The time taken for the number of radioactive nuclei in an isotope to halve
What does a short half life mean
The activity falls quickly because the nuclei are very unstable and rapidly decay
Why can a short half life be dangerous
Because of the high amount of radiation they emit at the star and quickly become safe
What does a long half life mean
The activity falls slowly because most of the nuclei dont decay for a long time
