Topic 1 - Quantum - Additional specification information Flashcards
3.2.2.2 - Collisions of electrons with atoms - additional information - ABOUT measuring ionisation energy.
What is measuring ionisation energy about?
Measuring the energy needed to ionise a gas atom.
What does the investigation of measuring the energy needed to ionise a gas atom include?
High speed electrons colliding with gas atoms in a sealed tube.
How is the high speed electron movement for collision created?
electrons are emitted from heated filament, and are attracted positive anode plate.
In the investigation of measuring ionisation energy of gas atoms, why does the gas need to be at sufficiently low pressure?
- Prevent too many atoms being present.
- As too many atoms would stop electrons from reaching anode side.
How would we increase the speed of the electrons?
By increasing the p.d. between the anode and filament.
When does the ammeter in the external circuit of the investigation get a current reading?
When the electrons from the filament reach the anode, and produce a charge flow in the external circuit.
When does ionisation occur, given that the electrons have been emitted from the heated filament in the tube?
- Electrons need to reach certain speed.
- As the electron arrives at anode to ionise gas atoms with enough KE.
What is the equation to calculate the ionisation of a gas atom in this experiment, given the p.d.
Ionisation energy of a gas atom = eV.
e = charge of electron.
V = p.d. between filament and anode when the current begins to increase, in the external circuit.
Why does the anode need to be positive relative to the filament?
To attract negatively charged electrons from the filament.
3.2.2.2 - Collisions of electrons with atoms - additional information - ABOUT deriving the equation for ionisation energy.
Electron-volt = energy gained by an electron when it has moved through a p.d. of 1 volt.
work done on charge = qV.
charge = q = e.
Therefore, the work done = qV = eV = electron-volt.
