Flashcards
Atomic Spectra
Flashcards do conjunto (20)
- 1Ionisation is .....When an atom loses or gains an electron to form an ion
- 2An ion is....A charge atom or molecule
- 3Ionisation can be caused by....A collision between a fast moving electron and an atom
- 4Excitation is when.....An electron is promoted into a higher energy level
- 5Excitation can happen when.....A collision with an external electron
Or by the absorption of a photon (electron absorbs photon) - 6De-excitation is when.....Electrons "relax" and drop down into a lower energy level
- 7De-excitation requires no.....External input
- 8What is emitted when de-excitation occurs?A photon
(note it can occur in steps with a photon being released at each step) - 9What is the emission spectrum?A series of coloured lines on a dark background due to excited atoms. This pattern is specific to different elements
- 10What is an emission spectrum discharge lamp?A bulb which contains helium gas and an electric current is passed through the helium. We get excitation which is then immediately followed by de-excitation
- 11Energy level diagram (straight line section from dot and cross diagram):
- 12Every element has.....Specific energy levels
- 13The energy of photons emitted from any element is always....The same and the energy must be equal to the difference between the 2 energy levels
- 14Energy levels have....Negative values
- 15To find the energy of the photon emitted we can use....hf = E1 - E2
hc/λ = E1 - E2 - 16E.g. if n=1 is -15.6eV and n=2 is -7.4eV then what is the energy of the photon emitted?-7.4-(-15.6) = 8.2eV
- 17If an electron absorbs a photon of specific energy, it can....Jump up 1 or more energy levels
- 18Shining continuous spectrum of light at a clod gas leads to....Discrete frequencies being absorbed by the electrons in the material
- 19The absorption spectrum is.....A series of dark lines on a continuous spectrum
- 20Only photons with an energy equal to a difference between 2 energy levels will be......Absorbed , and then possibly re-emitted in a random direction almost instantly