3.3 - collisions of e- with atoms Flashcards
define ionization energy
the energy required to remove an electron from the ground state from a atom
- ionising it
what type of state do atoms need to be in to be ionised
gas
give examples of ionisation
from radiation colliding with atoms, proving enough energy to remove the e-
ionization by electron collision with the gas in the fluorescent tube
define exitation
atoms absorbing energy, and e- promoted into higher energy levels
-without being ionised
describe an excited atom
an atom that has absorbed energy, causing an e- to be promoted from its ground state to a higher energy level
which is larger, excitation or ionisation energy
ionisation
excitation by electron collision diagram and description
define excitation energies
the energy values at which atoms absorb energy
what happens to a colliding e- if it doesn’t have enough Ek to cause excitation
its deflected off the atom without losing any Ek
how to measure excitation energies
- diagram and method/explination
- e- travel through the tube from cathode to anode and collide with the gaseous atoms
- If any Ek of the colliding e- remains it can be measured by increasing the P. D. between the anode and cathode until no current flow occurs
Current flow reduced if all Ek is absorbed to cause excitation
current flow unaffected if the e- are refected of the atoms
give the equation and define stopping potential
Ek(max) = Vs x e
(J) = (V) x (C)
the PD needed to stop the fastest moving e-
