inorganic chemistry

Question 1

how can EM radiation be described?

Answer 1

as both a wave and a particle- dual nature

Question 2

when does EM radiation behave as particles?

Answer 2

when it is absorbed or emitted, particles are called photons

Question 3

what do photons carry?

Answer 3

quantised energy, proportional to the frequency of radiation

Question 4

what happens when a photon is absorbed or emitted?

Answer 4

energy is gained or lost by the electrons of the material

Question 5

what happens when energy is transferred to atoms?

Answer 5

electrons within it may be promoted to higher energy level

Question 6

what happens when an electron moves from a higher to lower energy level?

Answer 6

a photon is emitted, the light energy emitted produces a spectrum that is made up of a series of lines at discrete energy levels

Question 7

wavelength definition

Answer 7

distance between two crests

Question 8

frequency definition

Answer 8

number of waves per second

Question 9

relationship between frequency and wavelength

Answer 9

as one increases, the other decreases - inversely proportional

Question 10

relationship between energy and frequency

Answer 10

frequency increases = energy increases

Question 11

what happens as the concentration of the compound in absorption spectroscopy increases?

Answer 11

intensity of radiation absorbed increases, intensity of radiation transmitted decreases

Question 12

what is an orbital?

Answer 12

an area of space where there is a 90% chance of finding an electron

Question 13

what tell us where in an orbital to find an electron?

Answer 13

quantum numbers

Question 14

what is a principal quantum number (n)?

Answer 14

represent electron shells
i.e n=1, first shell
n=2, second shell

Question 15

what are the four subshells?

Answer 15

s, p, d, f

Question 16

how many electrons can each orbital hold?

Answer 16

2

Question 17

angular momentum quantum number

Answer 17

s subshell = 0
p subshell = 1
d subshell = 2
f subshell = 3

Question 18

what does degenerate mean?

Answer 18

of equal energy

Question 19

magnetic quantum numbers

Answer 19

no. of orbitals = no. of possible magnetic quantum numbers e.g. 2p subshell could have -1,0 or +1
- you can choose any of the possible magnetic quantum numbers

Question 20

spin quantum numbers

Answer 20

• can either be +1/2 or -1/2
• the two electrons in an orbital will spin opposite ways

Question 21

pauli exclusion principle

Answer 21

no two electrons can have the same 4 quantum numbers

Question 22

aufbau principle

Answer 22

• orbitals of lowest energy fill up first
• lowest energy orbitals are not necessarily closest to the nucleus (4s fills up before 3d)

Question 23

hunds rule of maximum multiplicity

Answer 23

• each electron will take a separate orbital until all the orbitals in the subshell are half-filled

Question 24

what is ionisation energy?

Answer 24

energy required to remove one mole of electrons from one mole of gaseous atoms

Question 25

why does the first I.E of Beryllium not follow the trend?

Answer 25

removing an electron involves breaking a full subshell, which requires more energy

Question 26

what do full and half full shells provide for atoms?

Answer 26

more stability

Question 27

what is the best definition for a transition metal?

Answer 27

it can form at least one ion with an incomplete d subshell

Question 28

which elements dont match the definition for a transition metal?

Answer 28

scandium and zinc

Question 29

which two elements do not follow the aufbau principle and why?

Answer 29

copper and chromium, due to the special stability associated with subshells being full or half full

Question 30

which subshell are atoms lost from first when ions are formed?

Answer 30

4s

Question 31

oxidation number in a free or uncombined element

Answer 31

zero

Question 32

oxidation number in single atom ions

Answer 32

same as number charge on the ion

Question 33

oxidation number of hydrogen in compounds

Answer 33

usually +1 in hydrides it's -1

Question 34

oxidation number of oxygen in compounds

Answer 34

usually -2 in peroxides it's -1

Question 35

what must the sum of all the oxidation numbers in a molecule equal?

Answer 35

zero

Question 36

what must the sum of all the oxidation numbers in a polyatomic ion equal?

Answer 36

the overall charge on the ion

Question 37

what does an increase in oxidation number mean?

Answer 37

oxidation has occurred

Question 38

what does a decrease in oxidation number mean?

Answer 38

reduction has occured

Question 39

do compounds containing metals with a high oxidation number act as oxidising or reducing agents?

Answer 39

oxidising - they are reduced to a lower oxidation number

Question 40

do compounds containing metals with a low oxidation number act as oxidising or reducing agents?

Answer 40

reducing - they are oxidised to a higher oxidation number

Question 41

what is changing oxidation states often characterised by?

Answer 41

a change in colour

Question 42

what does a transition metal complex consist of?

Answer 42

a central metal ion surrounded by ligands

Question 43

what is a ligand?

Answer 43

a molecule or ion electron donor which bonds to the metal ion by the donation of one or more electron pairs to unfilled metal ion orbitals

Question 44

what are monodentate?

Answer 44

ligands which donate 1 electron pair

Question 45

what are bidentate?

Answer 45

ligands which donate 2 pairs of electrons - pairs must be from separate parts of the molcule, not the same atom

Question 46

what is a coordination number?

Answer 46

the number of bonds between the ligand and the central ion

Question 47

when naming complexes, when should -ate be added to the metal?

Answer 47

if overall charge on ion is negative

Question 48

dative covalent bonds

Answer 48

when one atom provides both electrons that form the covalent bond

Question 49

how are transition metal complexes able to absorb light?

Answer 49

due to the 5 degenerate d orbitals splitting in terms of energy

Question 50

why do the orbitals along the axis have a higher energy than the other in metal complexes?

Answer 50

because the ligands approach the metal along the axes and the electrons that lie on these axes will be repelled y those in the ligand molecules, resulting in more energy - called splitting of d orbitals

Question 51

relationship between ligand size and energy difference

Answer 51

larger ligand = larger energy difference

Question 52

what happens when compounds absorb light from the visible spectrum?

Answer 52

the colour corresponding to the wavelength is removed and the colour that remains is the complementary colour (opposite in the colour wheel)

Question 53

when are electron transitions more likely to occur in the UV part of the spectrum?

Answer 53

when the ligands are strong field (cause greatest splitting/highest energy difference)

Question 54

what colour will the compound be if the transitions occur in the UV part of the spectrum?

Answer 54

colourless

Question 55

why are zinc and scandium complexes colourless?

Answer 55

zinc (2+) has a full 3d subshell scandium (3+) has an empty 3d subshell

Question 56

2 categories of transition metal catalysts

Answer 56

homogeneous and heterogeneous

Question 57

homogeneous catalyst (definition)

Answer 57

catalyst that is in the same state as the reactants

Question 58

heterogeneous catalyst (definition)

Answer 58

catalyst that is in a different state to the reactants

Question 59

homogeneous catalyst (explanation)

Answer 59

changing oxidation states with the formation of intermediate complexes

Question 60

heterogeneous catalyst (explanation)

Answer 60

formation of activated complexes and the adsorption of reactive molecules onto active sites. the presence of unpaired electrons is thought to allow activated complexes to form, this can provide alternative reaction pathways with a lower activation energy.

Question 61

what is adsorption?

Answer 61

the "sticking" of a molecule onto the surface of a catalyst

Question 62

what happens to oxidation number when transition metals are used as catalysts?

Answer 62

oxidation number may change, but the original state will be regenerated at the end of the reaction

Question 63

why is the shape of a molecule important?

Answer 63

it will determine its properties and uses

Question 64

how do you calculate the number of electron pairs?

Answer 64

add the number of outer electrons on central atom to the number of atoms attached to the number of atoms attached to the central atom, then divide by 2

Question 65

what shape is a molecule with 2 bonded pairs?

Answer 65

linear

Question 66

what shape is a molecule with 3 bonded pairs?

Answer 66

trigonal planar

Question 67

what shape is a molecule with 4 bonded pairs?

Answer 67

tetrahedral

Question 68

what shape is a molecule with 5 bonded pairs?

Answer 68

trigonal bipyramidal

Question 69

what shape is a molecule with 6 bonded pairs?

Answer 69

octahedral

Question 70

what are the shapes of molecules or polyatomic ions determined by?

Answer 70

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