Atomic And Nuclear Physics Flashcards
What did the plum pudding model look like
Sphere of positive charge with negatively charged electrons doted around inside it.
What was Rutherfords alpha particle scattering experiment
Rutherfords team measured the deflection of alpha particles directed normally onto a sheet of very thin gold foil. The experiment was carried out in a vacuum. They discovered that most went through the gold foil. This proved that atoms have a lot of empty space. Some deviated through large angles and some were deflected back.
Define isotope
Atoms of the same element that have the same number of protons in their nucleus, but different number of neutrons.
Why are some atoms unstable
They have a certain combination or ratio of protons and neutrons which makes the nucleus unstable
Why are atoms known to be radioactive
Unstable nuclei will emit very nuclear radiation in an attempt to become stable
Define radiation
Disintegration of unstable nuclei by emitting alpha-particles, beta particles or gamma radiation randomly and spontaneously.
What is an alpha particle
A helium nuclei consisting of 2 protons and 2 neutrons
What is a beta particle
A fast moving electron
What is gamma radiation
A high energy electro magnetic wave
How do you work out an alpha decay equation
When an atom decays by alpha emission it losses 2 protons and 2 neutrons.
What happens when an atom decays by beta emission
It adds 1 to the atomic number
How to measure radiation
Use Geiger muller machine and measure doubt rate in 1 minute
To get final answer subtract background count per minute
How to prevent ionising radiation
S- shielding
T- minimise time
D- maximise distance
What is alpha radiation stopped by
Few cm in air or paper
What is beta radiation stopped by
Few meters in air and aluminium
