Half Lives Flashcards
What does a Geiger counter measure?
The radiation (photons or particles) emitted per second
What is the unit for measuring radiation?
Becquerels (Bq)
1 Bq = 1 count (wave or particle) per second
What is Half-life?
The time it takes for half the unstable nuclei to decay or for the activity to halve
What happens to atoms that decay?
They don’t disappear, they change to the atom of a different element and eventually become stable
What will the half-lives of different isotopes of an element be?
Different
What is net decline?
the ratio of the final to intial activity eg. after one half life the ratio will be 1:2, then after 2 it will be 1:4
What is a photon model?
In a photon model, electromagnetic radiation is emitted and absorbed as packets of energy called photons
What is the energy of each photon proportional to?
The frequency
What does an absorption spectrum show?
a set of frequencies of radiation absorbed by an atom when exited electrons move to higher energy levels
What can a photon that has enough energy do?
Completely remove and electron from the atom, the atom is ionised
Photons of what frequencies have enough energy to ionise atoms?
Ultraviolet, X-ray, Gamma ray frequencies
What does an emission spectrum show?
A set of frequencies of radiation emitted by an atom when exited electrons move to lower energy levels
What does the frequency of radiation emitted depend on?
The difference in energy of the energy levels
What happens if there are more than one energy changes?
If there are two changes then the emitted photons have less energy, lower frequencies and longer wavelengths
What is the largest energy difference from?
An energy level just below ionisation
