EM spectrum
gamma ray, x-ray, ultraviolet, visible, infrared, microwave, radio
What is the energy from light absorbed by?
Electrons in the substance
What do electrons gain or lose energy depending on?
If they are absorbing or releasing energy
What can EMR be considered as?
A stream of photons
The energy of a single photon is related to wavelength and frequency by?
E= hf
What is h (plancks constant)?
6.626 x 10^-34 Js
For one mole of photons?
E = Lhf
What is L (Avogadro's number)?
6.02x10^23
the absorbed frequencies appear as _____ lines in the visible light spectrum
black
What is a quanta?
the amount of energy needed to move from one energy level to another
Electrons can absorb energy to be?
Promoted to a higher energy level
Ionisation energy is the point on a spectra where?
The lines converge
When electrons return to lower energy levels?
A photon of light is emitted
For an emission spectrum?
Electrons become excited, electrons return to lower energy level emitting light
Each line on a spectrum is?
A transition between energy levels
The intensity of the absorption or emission can determine?
The concentration of the sample
What is an atomic orbital?
a region of space in which there is a high probability of finding an electron
Each electron can be located by?
4 quantum numbers
The principle quantum number? (n)
Starts at 1 and increases by 1 every period on the periodic table
The angular momentum number? (l)
shape of orbital
L= 0
s orbital
L=1
p orbital
L=2
d orbital
L=3
f orbital
What shape are s orbitals?
spherical
How many electrons does each orbital hold?
2 electrons
The higher the number of the energy level in an s orbital?
The larger the sphere
What shape are p orbitals?
dumbbell shaped
Define degenerate
Same energy as each other
What angle are p orbitals from each other?
Right angles
How many orientations does d orbitals have?
5
Magnetic quantum number? (Ml)
describes the orientation of the orbital in space (-l to +l)
Spin quantum number? (Ms)
+1/2 or -1/2
What is the Pauli Exclusion Principle?
no two electrons in the same atom can have the same set of four quantum numbers, each subshell can hold a max of 2 electrons, they must have opposing spins
What is the Aufbau principle?
Electrons fill orbitals in order of increasing energy
spectroscopic notation
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6, 5s2, 4d10....
To quantify the intensity of colour, absorbance of samples of known conc are measured...
1. Create calibration graph, 2. Draw a straight line through graph, 3. Measure the absorbance of unknown sample and compare to graph