Inorganic and Physical Chemistry Flashcards
What is the unit for the energy in one mole of photons
kJ mol^-1
What is the unit for the energy of a photon
Joules (J)
What equation gives the energy in one mole of photons
E=Lhf/1000
How is atomic emission spectra produced
An electron drops from a higher to a lower energy level, releasing a quantised amount of energy in the form of a photon.
How is atomic absorption spectra produced
A photon is incident on an atom and it’s energy promotes an electron from a lower to a higher energy level.
How many electrons can an atomic orbital hold
2
The four quantum numbers and their symbols are
principal (n), angular momentum (l), magnetic (m) and spin (s)
subshells that have the same energy are called
degenerate
aufbau principle
electrons fill orbitals in order of increasing energy
pauli exclusion principle
no two electrons in an atom have the same four quantum numbers
hund’s rule
when degenerate orbitals are available, electrons fill each orbital singly and with parallel spin before pairing up to fill the orbitals
2 electron pairs, shape and angles
linear, 180°
3 electron pairs shape and angles
trigonal planar, 120°
4 electron pairs shape and angles
tetrahedral, 109.5°
5 electron pairs shape and angles
trigonal bipyramidal, 120° and 90°
6 electron pairs shape and angles
octahedral, 90°
why is water bent and not linear
the non-bonding pairs of electrons create a greater repulsion, reducing the bond angles between the hydrogens
why don’t copper and chromium follow the aufbau principle
an electron from the 4s subshell is promoted to form a more stable half filled or full 3d subshell
oxidation
an increase in oxidation number
reduction
a decrease in oxidation number
transition metal complexes consist of
a central metal ion surrounded by ligands
what are ligands
negative ions or uncharged molecules with one or more non-bonding pairs of electrons
what are dative bonds
where both electrons in a bond are donated by one atom
monodentate, bidentate, hexadentate ligands have
1, 2 and 6 pairs of non-bonding electrons respectively
splitting of d orbitals
when ligands approach the metal ion along the x, y and z axes, the electrons that lie on the axes gain energy so the d orbitals are ‘split’ no longer degenerate
splitting of d orbitals allows
transition metals to absorb light
energy difference between ‘split’ d orbitals depends on
the position of the ligands in the electrochemical series
heterogeneous catalysts
are in a different state to the reactants
homogeneous catalysts
are in the same state to the reactants
in a chemical equilibrium
the rate of the forward and reverse reaction are equal and the concentration of the products and reactants are constant
equilibrium position is affected by
temperature, concentration of products or reactants and if there and different moles of gasses on both sides, pressure
heterogeneous equilibrium
not all the species are in the same state
homogeneous equilibrium
all the species are in the same state
what affects the value of k
K is only affected by temperature
affect of endothermic and exothermic reactions on equilibrium
endothermic favours products so K increases, exothermic favours reactants so K decreases
amphoteric
substances that can act as both acids or bases
strong acids
nitric acid, sulphuric acid and hydrochloric acid, dissociate fully (ionise) in water and the reaction is irreversible
weak acids
carboxylic acids, carbonic acid and sulphurous acid, dissociate partially in water and the reaction is reversible
monoprotic and diprotic acids
contain one and two hydrogen atoms per molecule respectively
strong bases
oxides and hydroxided of the alkali metals and soluble oxides and hydroxides of the group 2 metals, dissociate fully (ionise) in water and the reaction is irreversible
weak bases
amines, dissociate partially in water and the reaction is reversible
neutral salts
acidic salts
alkaline salts
a strong acid and a strong base
a strong acid and a weak base
a strong base and a weak acid
what are soaps
salts of fatty acids (weak acids) and strong bases
acid
proton donor
base
proton acceptor
conjugate acid
the species left over when bases accept a proton
conjugate base
the species left over when acids donate a proton
buffer solution
a solution where the pH remains approximately constant when small amounts of acid, base or water are added
acid buffer solution consists of
a weak acid and one of its salts
basic buffer solution consists of
a weak base and one of its salts
indicators
are used in acid-base titrations as they change colour at the end-point of the reaction. usually weak acids in which the colour of the acid varies from its conjugate base
entropy
measure of the amount of disorder within a system
feasible reactions
tend towards the products rather than the reactants, the total entropy must increase
for a reaction to be feasible
the free energy change must be less than zero
