2. Inorganic Chemistry

what are the formulas for the energy associated with 1 mole of photons

E = Lhf

E = Lhf/λ

how can electromagnetic radiation be described and characterised as

in terms of waves and in terms of wavelength and/or frequency

what is the formula for the relationship between wavelength and frequency

c = fλ

what are ways electromagnetic radiation can be described as

wave

particle

what is electromagnetic radiation said to have

dual nature

what happens when electromagnetic radiation is absorbed or emitted by matter

it behaves like a stream of particles with the particles being photons

what level of energy does a photon carry

energy proportional to the frequency of radiation

what happens when a photon is absorbed or emitted

energy is gained or lost by electrons in the substance

whats the difference between photons of higher frequency compared to those with lower frequency

can transfer a greater amount of energy

what are the formulas used for a single photon

E = hf

E = hc / λ

what might happen when energy is transferred to atoms

electrons within the atoms may be promoted to higher energy levels

when does an atom emit a photon of light

when an excited electron moves from a higher energy level to a lower energy level

what does light energy emitted by an atom produce

a sprectrum made up of a series of lines at discrete energy levels

what does each element create in terms of spectra

produces characteristic absorption and emission spectra so they can be used to identify and quantify the element

how is radiation absorbed in absorption spectroscopy

as electrons are promoted to higher energy levels

how is an absorption spectrum produced

by measuring how the intensity of absorbed light varies with wavelength

how are electrons excited in emission spectroscopy

high temperatures

how is an emission spectrum produced

an electron is promoted to a higher energy level

when it falls back to a lower state energy is emitted

how is the concentration of an element found in atomic spectroscopy

the intensity of light emitted or absorbed

how can the discrete lines observed in atomic spectra be explained

if electrons display the properties of both particles and waves

how do electrons behave

as standing waves in an atom, theyre waves that vibrate in time but dont move in space

what are orbitals

the different sizes and shapes of waves around the nucleus

how many electrons can an orbital hold

2

what different shapes of orbitals are there

s

p

d

f

what is the shape of s orbitals

all spherically symmetrical

what happens to the electron density of s orbitals when the value of n increases

concentrated further out from the nucleus

how many electrons can be occupied in an s orbital

2

what value of n do p orbitals begin with

2

how many p orbitals do each principal energy shell contain

3

how can electrons in p orbitals be described

more difficult to describe as the probability of finding them isnt spherically symmetrical around the nucleus

for p orbitals where is the probability of finding an electron

concentrated in 1 direction

what does degenerate mean

of same/equal energy

what are the 3 degenerate p orbitals called

p_x, p_y, p_z

at what angle do p orbitals lie

right angles of each other

how many electrons can a p orbital have

2 in each so maximum of 6

what value of n do d orbitals begin with

3

how many d orbitals are in each principal energy level

5

how many electrons can be held in a d orbital

2 electrons in each so maximum of 10

what are the shapes of each s orbital

what are the shapes of each p orbital

what are the shapes of each d orbital

what is quanta

electrons within atoms have fixed amounts of energy

what is the principal quantum number, n

the main energy level for an electron

how many electrons can be in each shell as n increases

2 when n = 1

8 when n = 2

18 when n = 3

32 when n = 4

what does the angular momentum quantum number, I do

determines the shape of the orbital in which the electrons are contained

what happens as the value of l increases

s subshell if l = 0

p subshell if l = 1

d subshell if l = 2

f subshell if l = 3

what happens to l when n increases

n = 1 so l  =  0, the first shell has 1s subshell 

n = 2 so l  =  1, the second two subshells 2s, 2p 

n = 3 so l  =  2, the third shell has three subshells 3s, 3p, 3d 

n = 4 so l =   3, the fourth shell has four subshells 4s, 4p,4d, 4f

what is the magnetic quantum number m_l

determines the orientation of the orbital

what happens to the m_l as l increases

l  =  0 s subshells do not split, m_l  =  0 (one s orbital) 

l  =  1 p subshells split into three p orbitals -  p_x, p_y, p_z, m_l  =  -1,  0,  +1  

l  =  2 d subshells split into five d orbitals -  d_xy, d_xz, d_yz, dx²-y², dz², m_l  =  -2,  -1,  0,  +1,  +2  

l  =  3 f subshell split into seven f orbitals - m_l  =  -3, -2,  -1,  0,  +1,  +2. +3 

what is the spin magnetic quantum number m_s

determines the direction of spin

what values can m_s have

+½ or -1/2

what does the aufbau principle principle state

electrons fill orbitals in order of increasing energy

what is hunds rule

when degenerate orbitals are available, electrons fill each singly, keeping their spins parallel before spin pairing starts

what is the pauli exclusion principle

no two electrons in one atom can have the same set of four quantum numbers, therefore, no orbital can hold more than two electrons and these two electrons must have opposite spins

what are all orbitals classed as in an isolated atom

degenerate

what are the 2 unusual elements due to their electronic configurations

chromium

copper

why are chromium and copper unusual

3d and 4s subshells are close together in energy and theres a special stability associated with all 5 d orbitals being half or completely filled

when do you know if an electronic configuration is in an excited state

if an atoms electronic configuration doesnt correspond to the one that would be given

what should you look out for when filling in electronic configurations

4s is filled in and empties before 3d

what is the periodic table divided into

how can the variation in ionisation energies in the first 36 elements be explained

in terms of the relative stability of different subshell’s electronic configurations

what is the relationship between stability of an electronic configuration and ionisation energy

the more stable the electronic configuration, the higher the ionisation energy

what can VSEPR be used to predict

the shapes of molecules and polyatomic ions

what are the steps to finding the number of electron pairs surrounding a central atom

taking the total number of outer electrons on the central atom and adding one for each atom attached

adding an electron for every negative charge

removing an electron for every positive charge

dividing the total number of electrons by two to give the number of electron pairs

how are electron pairs arranged

in a way to minimise repulsion and maximise separation

what is the arrangement of electron pairs when there are 2 electron pairs

linear (180°)

what is the arrangement of electron pairs when there are 3 electron pairs

trigonal planar (120°)

what is the arrangement of electron pairs when there are 4 electron pairs

tetrahedral (109.5°)

what is the arrangement of electron pairs when there are 5 electron pairs

trigonal bipyramidal (120° and 90°)

what is the arrangement of electron pairs when there are 6 electron pairs

octahedral (90°)

how are the shapes of molecules or polyatomic ions determined

by the shapes adopted by the atoms present based on the arrangement of electron pairs

whats the order of electron pair repulsion in terms of decreasing strength

non-bonding pair/non-bonding pair > non-bonding pair/bonding pair > bonding pair/bonding pair

what are transition metals

metals with an incomplete d subshell in at least 1 of their ions

how can the oxidation number be found

uncombined elements have an oxidation number of 0

ions containing single atoms have an oxidation number that is the same as the charge on the ion

in most of its compounds, oxygen has an oxidation number of −2

in most of its compounds, hydrogen has an oxidation number of +1

the sum of all the oxidation numbers of all the atoms in a neutral compound must add up to zero

the sum of all the oxidation numbers of all the atoms in a polyatomic ion must be equal to the charge on the ion

what can oxidation be defined as in terms of oxidation number

an increase in oxidation number

what can reduction be defined as in terms of oxidation number

a decrease in oxidation number

what type of agent are compounds with high oxidation states

oxidising agents

what type of agent are compounds with low oxidation states

reducing agents

what do transition metal complexes consist of

a central metal atom/ion surrounded by ligands

what can ligands be

negative ions

molecules with non-bonding electron pairs

what happens to the non-bonding electron pairs in ligands

theyre donated to the central metal atom/ion forming dative covalent bonds

what are dative covalent bonds

a covalent bond where both electrons are donated by the same atom

what can ligands be classified as

monodentate

bidentate up to hexadentate

what does the coordination number mean

the total number of bonds from the ligands to the central transition metal

what is H₂O called when naming complexes

aqua

what is NH₃ called when naming complexes

ammine

why are ammonia and water classed as mondentate ligands

forms only one bond to the metal

what is CO called when naming complexes

carbonyl

what happens to the names of negative ions

“ide” should be changed to “ido”

“ite” or “ate” to “ito” or “ato”

how should ligands be listed

alphabetically by the name

what happens to the name of metals when the overall complex is negative

“ate” is added

what are the latin names used for metals in negative complexes

iron → ferrate

copper → cuprate

what happens to d orbitals in a complex of a transition metal

they no longer degenerate

how does the splitting of d orbitals into higher and lower energies occur

when electrons present in approaching ligands cause the electrons in the orbitals lying along the axes to be repelled

what are strong field ligands

ligands that cause a large difference in energy between subsets of d orbitals

what are weak field ligands

ligands that cause a small energy difference between subsets of d orbitals

what is the spectrochemical series

when ligands are placed in an order of their ability to split d orbitals

how can the colours of many transition metal complexes be explained

in terms of d-d transitions

how is light absorbed in transition metals

when electrons in lower energy d orbitals are promoted to a d orbital of higher energy

what happens when the light of 1 colour is absorbed

the complementary colour will be observed