CH3Arrangement of electrons in the atom Flashcards
Outline bohrs atomic theory based on the hydrogen emission spectrum.
- Electrons are restricted to energy levels where they have a quantised energy.
- Electrons occupy the ground state.
- If a fixed amount of energy is absorbed, the electron can jump to a higher energy level.
- Electrons fall back down to a lower energy level and emit photons of light at a specific frequency.
- Each element has different distributions of energy levels, which give rise to different electronic transitions, and unique emission / absorption spectra
What colour do the following metals give off in the flame test?
1. lithium
2. potassium
3. barium
4. strontium
5. copper
6. sodium
- crimson
- lilac
- green
- red
- green blue
6.
Energy level
The fixed energy value that an electron in an atom may have
Ground state
Of an atom is one in which the electrons occupy the lowest available energy level
Excited state
Of an atom, is one in which the electrons occupy higher energy levels than those available in the ground state.
e2-e1=hf
E2= energy of higher energy level
E1- Energy of lower energy level
h=plancks constant
f= frequqncy of light
Atomic orbital
A region in space within which there is a high possibility of finding an electron (95%).
Balmer series
Electron transitions are from higher energy levels to n=2
give rise to lines in the visible spectrum
Lyman series
Electron transitions are from hgher energy levels to n = 1
give rise to lines in the ultraviolet region of the spectrum
Patschen series
Electron transition are from higher energy levels to n=3
give rise to lines in the infrared region of the spectrum.
Sublevel
A subdivision of a main energy level, and consists of one or more orbitals of the same energy.
Heisenbergs uncertainty Principle
It is impossible to measure at the same time both the position and velocity of an electron
Limitations of Bohrs Theory
-Worked for hydrogen, but not for atoms with more electrons
-Wave- Particle duality
-Heisenberg’s Uncertainty Principle
-Sublevels
Who was Erwin Schrotwoosdinger
Devised mathematical equations to work out the probability of finding an electron in any particular sublevel in any atom.
Gave us the shapes of the four types of robitals
Four types of orbitals
SPDF
S orbitals
-spherical - the probability of finding an electron is identical in all directions from the nucleus
- Differ in size
P orbitals
- dumb-bell shaped
- Each p sublevel consists of three parts px, py and pz
-these orbitals differ in orientation in space - The orbitals are at 90 degree right angles to each other
Louis de Broglie
Suggested all moving particles had a wave motion associated to them.
Wave- particle duality
The concept that electrons behave like waves and like particles.
Reasoning for heisenbergs uncertainty principle
If a beam of light is used to detect an electron, the beam strikes the electron, immediately changing its velocity as it has such a small mass.
Why was ernest rutherfords proposal too simple
He proposed electrons revolved around the nucleus, however , the eletrons would spiral into the nucleus and atom would collapse.
Spectrometer vs spectroscope
Both are used to observe spectra however
Spectrometer can measure wavelengths of light.
Emssion spectrum appearance
Coloured lines on a dark background
Absorption spectrum appearance
Dark lines on a coloured backgroundses
Uses for aas
- water analysis Pb Hg Cd
- blood analysis Pb
- forensics -> gunshot residue Pb Sb Ba
What is atomic absorption spectrometry
Analytical technique used to measure the concentration of elements.
What were bohrs observations and explained
-Elements emit only certain frequencies of light
-Bohr suggests that the electrons in atoms can only have a fixed amount or quantised energy
Flame test use
Used to identify metals present in unknown compounds
