P6.1 Flashcards
What are the relative mass and charge of the different subatomic particles
Proton 1 +1
Neutron 1 0
Electron 0.0005 -1
What are isotopes
Isotopes are different number of neutrons but the same number of protons and electrons
How to calculate amount of neturons
Mass number - atomic number
Why do nuclei of atoms emit radiation
Because they are unstable and emit radiation. This radiation can be made up of particles and waves.
What is alpha radiation
It’s a particle, symbol a, it’s the nucleus of a helium atom, 4 2 He
What is beta radiation
It’s a particles, symbol B, a fast moving electron, 0 -1 e
What is gamma radiation
Electromagnetic wave, Y, a wave of the electromagnetic spectrum
What is neutron radiation
It’s a particle, N, a particle in the nucleus, 1 0 n
What is the bottom number and the top number
Is the charge and the top number the relative atomic mass
How does beta radiation occur
A nucleus doesn’t have electrons in it so it decays to form a proton and electron.
What is a geiger counter
A geiger counter is a device that clicks when radiation enters it. A click is a current produced when the radiation ionises the gas inside the tube.
What radiation has the lowest penetrative power
Alpha particles have the lowest penetrative power and can be stopped by a few sheets of paper.
What radiation has the medium penetrative power
Beta particles have the medium penetrative power and can be stopped by a few mm of aluminium.
What radiation has the highest penetrative power
Gamma particles have the highest penetrative power and can be stopped by a few cm of lead.
What is the order of the radiation in ionising power
Alpha, Beta, Gamma
What can radiation do
Radiation is ionising and can remove electrons from atoms forming positively charged ions.
Why are alpha particles the most ionising
Alpha particles are the most ionising as they transfer more energy to the material they are travelling through.
What is the general formula for alpha decay
DRAW IT
What do you have to make sure of in a nuclear equation
The charges and masses need to add up.
What is the formula for beta decay
DRAW IT
What is the formula for neutron emission
DRAW IT
When does material emit radiation (time wise)
it emits radiation randomly
What does a geiger counter measure
A geiger counter can measure the radiation (photons or particles) emitted per second. This is called activity, or count rate, of the sample, and is measured in (Bq).
What is one Bequerel
The count per second
What is the half life
The time it takes for the activity to halve is the half life. This is the same time for the nuclei of half the atoms to decay.
Why is half life constant
Is constant because the probability that any one nucleus decays in one second is fixed.
What happens when atoms decay
They change to the atom of a different element. They eventually become stable.
What do electrons do
They occupy specified energy levels around the nucleus of the atoms. They occupy the lowest energy level at the smallest distance from the nucleus.
What is the energy in each photon proportional to
Its proportional to the frequency
What does an absorption spectrum show
Shows the set of frequencies of radiation absorbed by an atom when excited electrons move to higher energy levels.
When a photon has enough energy what happens
It can completely remove an electron from the atom and it becomes ionised.
How can you excite electrons
By passing a current through it.
What happens when a electron move down radiation levels
They emit radiation.
What does an emission spectrum show
An emission spectrum shows a set of frequencies of radiation emitted by an atom when it does it.
What does the frequency of radiation emitted depend on
It depends on the difference in energy of the energy levels. The largest energy difference is from energy level just below ionisation.
What are gamma rays
Gamma rays are the highest energy radiation.
