Arrangement Of Electrons In Atom (chpt. 3) Flashcards
What is an emission line spectrum
When light passes through a prism it splits to give a continuous spectrum
Each element has a unique emission line spectrum
FLAME TEST EXPERIMENT (lithium, potassium, barium, strontium, copper, sodium)
page 14 in book
Lithium - crimson
Potassium - lilac
Barium - green
Strontium - red
Copper - blue/green
Sodium - yellow
What was the Bohr theory
Electrons revolve around the nucleus in fixed paths
Electrons in any one orbit have a fixed amount of energy
Energy of an electron is quantised - fixed at a definite value
Energy level
The fixed energy value an electron in an atom may have
Ground state
The ground state of an atom is one in which the electrons occupy the lowest available energy level
Excited state
When the electrons occupy higher energy levels than those available in the ground state
Electrons jump from lower energy levels to higher energy levels
Colours in line emmision spectrum
n = 3,4,5 - infrared region
n = 2 - balmer series
n = 1 - ultraviolet region
Explain why each element has a unique line emission spectrum
Each element has a different number of electrons and has its own arrangement of these electrons in energy levels
Emission spectrum
Coloured lines against a dark background
Absorption spectrum
Dark lines against a coloured background
Atomic absorption spectrometer ?
Atoms of an element in the ground state absorb light of a particular wave length that is characteristic/ unique to the element
The amount of light absorbed is directly proportional to the concentration of the element present in the sample
What is a sub level
A subdivision of a main energy level and consists of one or more orbitals of the same energy
Heisenbergs uncertainty principle
States that it is impossible to measure at the same time both the velocity and position of an electron
Wave - particle duality
Electrons have a wave motion associated with them
De Brogelie
What were the limitations of Bohr’s theory
- Did not take wave motion into account
- Did not take sublevels into account
- Was in conflict with Heisenberg’s Uncertainty Principle
