How can electromagnetic radiation be described
wavelength and frequency
Electromagnetic radiation is said to have …..
dual nature
what is a photon
quantised energy proportional to the frequency of radiation
photons in high frequency have …. energy compared to low frequency
greater
What happens when a photon of light is emitted
after excited electrons are promoted to a higher energy level they fall back to lower energy levels emitting a photon of light
describe the appearance of emission and absorption spectrum
emission - black background with coloured lines
absorption - coloured background with black lines
what does absorption spectrum measure
the intensity of absorbed light at different wavelengths
what does the emission spectrum measure
the intensity of emitted light at different wavelengths
what is the principle quantum number (n)
indicates the main energy level for an electrons and is related to the size of the orbital
what is the angular momentum quantum number (l)
determines the shape of the subshell
what is the magnetic quantum number (m1)
determines the orientation of the orbital
what is the spin magnetic quantum number (ms)
determines the direction of spin
what is the aufbau principle
electrons fill orbitals in order of increasing energy
what is hund’s rule
when degenerate orbitals are available electrons fill signally before together
What does degenerate mean
of equal energies
what is pauli’s principle
no orbital hold more than two electrons and they must spin in opposite directions
what are the 4 blocks of the periodic table
s, p, d, f
what does half-filled and full subshells suggest? and why?
higher ionisation energy because they have more stable electron configurations
why do negatively charged electrons repel each other
they are arranged to minimise repulsion and maximise separation
linear
2 bonding and no non-bonding
bond angle - 180
trigonal planar
3 bonding pairs no non-bonding pairs
bond angle - 120
tetrahedral
4 bonding pairs no non-bonding pairs
bond angle - 109.5
trigonal pyramidal
3 bonding pairs and 1 non-bonding pair
bond angle - 107.5
angular
2 bonding pairs and 2 non-bonding pairs
bond angle - 104.5
trigonal bipyramidal
5 bonding pairs and no non - bonding pairs
bond angle - 120
octahedral
6 bonding pairs and no non-bonding pairs
bond angle - 90 and 180
put order of repulsion in decreasing order
non-bonding/non-bonding pair
non-bonding/bonding pair
bonding/bonding pair
what is the definition of a transition metal
have incomplete d-subshell in a least one of their ions
Why are chromium and copper exception to aufbau principle
exempt due to special stability associated with d shell being half-filled or completely filled
what subshell do transition metals lose from first
4s rather than 3 d
all noble gases are characterised by the competition of outermost orbital. This orbital is
s or p orbitals
name Na3[Co(f)6]
sodium hexafluoridocolbalt (III)
how can oxidation be defined
increase in the oxidation number
how can reduction be defined
decrease in oxidation number
What is a ligand
A ligand is a molecule with at least one non-bonding pair of electrons available for bonding with a metal ion
ligand can be classed as
monodentate, bidentate up to hexadentate
what is the coordination number
the total number of bonds form the ligand to the central atom
what is a weak filed ligand
ligand which causes a small difference in energy between subsets of d orbital
what is a strong filed ligand
causes a large difference in energy between subsets of d orbitals
what colour is observed if magenta is being emitted
green light
what are heterogenous and homogeneous catalysts
homo - same state as reactant
hetro - different state form reactant
