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structure 3 Flashcards

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1
Q

What are periods?

A

horizontal columns on the periodic table

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2
Q

What are groups?

A

vertical columns on the periodic table

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3
Q

Where are the blocks located?

A

S - left hand side
P - right hand side
D - middle
F - bottom

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4
Q

What are metalloids?

A

elements with physical properties of metals and chemical properties of non-metals

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5
Q

What are examples of metalloids?

A

Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium

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6
Q

What do valence electrons show?

A

group number

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7
Q

What do energy levels show?

A

period number

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8
Q

What are the properties of negative ions?

A

larger than parents atom as an electron has been added to the outer shell, so there is a decrease in ENC and reducing ionic radius

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9
Q

What is first ionization energy?

A

energy required to remove 1 mole of electrons from 1 mole of atoms in the gaseous state

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10
Q

What happens to ionization energy down the group?

A

ionisation energy decreases down the group as the electrons is further away from the nucleus, meaning there is more shielding and a weaker attraction, requiring less energy to remove

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11
Q

What are the properties of group 7?

A

halogens with valence electrons occupying p orbitals

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12
Q

What are the properties of group 0?

A

noble gases that are inert and colourless with a full stable electronic configuration

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13
Q

What are the properties of group 1?

A

alkali metals with valence electrons that occupy an s subshell

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14
Q

What is periodicity?

A

physical and chemical properties repeat periodically in the periodic table

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15
Q

What is effective nuclear charge?

A

net positive change experienced in a multi electron atom
ENC = proton number - electrons in previous noble gas

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16
Q

What happens to ENC across the period?

A

ENC increases across the period as there is an increased number of protons in the nucleus with the same amount of shells and shielding

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17
Q

What happens to ENC down the group?

A

ENC decrease down the group as there is more shells and shielding so there is a weaker attraction between the outer electron and nucleus

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18
Q

What is shielding?

A

reduction of attractive forces between the nucleus and outer electrons by inner electron shells

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19
Q

What is ionic radius?

A

half the distance from the nucleus to the outer electron

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20
Q

What happens to atomic radius down the group and across the period?

A

down the group - increases as the number of energy levels increases
across the period - decreases as ENC increases which pulls in the electrons more tightly

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21
Q

What are the properties of positive ions?

A

smaller than parent atom as an electrom has been removed from the outer shell, causing an increase in ENC and reducing ionic radius

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22
Q

What is atomic radius?

A

half the distance between neighbouring nuclei in a covalent bond

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23
Q

What is second ionization energy?

A

energy required to remove an extra mole of electrons from 1 mole of gaseous ions

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24
Q

What happens to ionic radius down the group and across the period?

A

down the group - increases as energy levels increase
across the period - decreases as ENC increases

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25
Q

What happens to ionization energy across the period?

A

ionisation energy increases as ENC increases and there is a greater attraction, requiring more energy to overcome

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26
Q

What is second electron affinity?

A

energy change when 1 mole of electrons is added to 1 mole of gaseous ions

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27
Q

What is electron affinity?

A

energy change when 1 mole of electrons is added to 1 mole of gaseous atoms

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28
Q

What happens to electron affinity down the group?

A

electron affinity decreases due increased energy levels which means there is a weaker attraction between the nucleus and outer electron

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29
Q

What happens to electronegativity across the period?

A

increases across the period due to increased ENC, meaning there is a higher attraction between bonding electrons and the nucleus

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30
Q

What happens to electron affinity across the period?

A

increases across the period as ENC increases meaning there is a greater attraction between the nucleus and outer electron

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31
Q

What is electronegativity?

A

measure of the availability to attract a pair of electrons in a covalent bond - measure of the attraction between the nucleus and outer electron

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32
Q

Why is N and O an exception to ionization energy?

A

oxygen has a lower IE as a pair of electrons is easier to remove than 1 due to the spin pair repulsion

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33
Q

What happens to electronegativity down the group?

A

decreases as there are more wheels between bonding electron and nucleus, meaning there is a lower attraction

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34
Q

Why is B and Be an exception?

A

Boron has a lower IE as electrons are more easily lost from the 2p orbital

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35
Q

What is the Pauling scale?

A

assigns electronegativity values to each element

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36
Q

What are physical properties of group 1?

A
  • good conductors of electricity and heat
  • low density
  • shiny grey surface when freshly cut
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37
Q

What are the reactions of group 1 with water?

A

produces a salt and hydrogen, dissolves, melts into a sphere and produces a flame
2K (s) + 2H2O (l) –> 2KOH (aq) + H2 (g)
2KOH splits into 2K+ and 2OH -

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38
Q

What are chemical properties of group 1?

A
  • very reactive metals
  • increase in metallic character across the period
  • form ionic compounds with non-metals
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39
Q

Why are group 1 conductors?

A

contain delocalised electrons which can move around the structure and carry charge

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40
Q

What bonding is present with group 1?

A

metallic bonding- attraction between positive ion and a sea of delocalised electrona

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41
Q

What happens to reactivity down group 1?

A

reactivity increases down the group as there is more shielding and a lower IE meaning it requires less energy to overcome

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42
Q

What are physical properties of group 7?

A

Fl - pale yellow gas
Cl - yellow-green gas
Br - red-brown liquid
I - purple gas, brown liquid, grey crystal

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43
Q

What happens to boiling point down group 1?

A

decreases as the atomic radius increases so there is a weaker attraction and requires less energy to overcome

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44
Q

What are the half-reactions of group 1?

A

Li –> Li+ + e-

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45
Q

Why is rubidium more reactive than Na?

A
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46
Q

What are the half-equations for group 7?

A

Cl2 + 2e- –> Cl

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47
Q

What are chemical properties of group 7?

A
  • very reactive non metals
  • forms ionic compound with group 1
  • forms covalent compounds with non-metals
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48
Q

What happens to reactivity down group 7?

A

decreases due to high ENC and a very exothermic electron affinity which decreases due to increased shielding and atomic radii requiring more energy to overcome

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49
Q

What happens to melting points down group 7?

A

increases as there are more electrons and LDF which require more energy to overcome

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50
Q

What bonding is present in group 7?

A

covalent bonding and london dispersion forces

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51
Q

What are displacement reactions?

A

when a more reactive element displaces a less reactive element from it’s compound

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52
Q

What is produced when a group 7 reacts with silver nitrate?

A

precipitation reaction where silver ions react with halide ions to form coloured precipitates
Cl - white
Br - cream
I - yellow
Ag+ (aq) + X- (aq) –> AgX (s)

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53
Q

What are properties of noble gases?

A

colourless, monotonic gases that are inert

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54
Q

How do basic oxides react with water?

A

dissolve in water to from alkaline solutions due to the formation of OH- ions

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55
Q

Why are noble gases so unreactive?

A

don’t form + ions - high IE and ENC so don’t lose electrons easily
don’t form - ions - electron would be added to a shell with lots of shielding and would get lost

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56
Q

What is the trend of period 3 from left to right?

A

continuum from basic metal oxides (Na2O, MgO) that are ionic to amphoteric oxides (Al2O3) to acidic non-metal oxides (SiO2, P4O10, SO3, Cl2O7) which are covalent

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57
Q

What colors are produced when silver nitrate reacts with Cl, I and Br?

A

Cl - white
Br - cream
I - yellow

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58
Q

How do phosphorus oxides react with water?

A

P4O10 (s) + 6H2O (l) –> 4H3PO4 (aq) - phosphorus (V) oxide
P4O6 (s) + 6H2O (l) –> 4H3PO3 (aq) - phosphorus (IV) oxide

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59
Q

How do basic oxides react with acid?

A

react with acids to form salt and water - oxide reacts with hydrogen
MgO (s) + 2HCl (aq) –> MgCl2 (s) + H2O (l)
O2- (s) + 2H+ (aq) –> H2O (l)

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60
Q

How does silicon dioxide react with water?

A

SiO2 (s) + 2OH- (aq) –> SiO3 2- (aq) + H2O (l) - forms silicates with alkalis

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61
Q

How does carbon dioxide react with water?

A

CO2 (g) + H2O (l) –> H2CO3 (aq) - carbonic acid

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62
Q

How does sulfur trioxide react with water?

A

SO2 (g) + H2O (l) –> H2SO3 (aq) - sulphuric IV acid)

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63
Q

What does amphoteric mean?

A

shows both acid and base properties

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64
Q

How does sulfur dioxide react with water?

A

SO3 (g) + H2O (l) –> H2SO4 (aq) - sulphuric (VI acid)

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65
Q

How does an amphoteric oxide react with acids?

A

Al2O3 (s) + 3H2SO4 (aq) –> Al2(SO4)3 (aq) + 3H2O (l) - acts as a base

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66
Q

How does an amphoteric oxide react?

A
  • doesn’t react with water as it is insoluble
  • reacts with alkalis to form concentrated silicates
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67
Q

How does an amphoteric oxide react with a base?

A

Al2O3 (s) + 3H2O (l) + 2OH- (aq) –> 2Al(OH)4- (aq) - acts as an acid

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68
Q

How does Cl2O7 and Cl2O react with water?

A

Cl2O7 (s) + H2O (l) –> 2HClO4 (aq) - chloric (VII) oxide
Cl2O (s) + H2O (l) –> 2HClO (aq) - chloric (I) oxide

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69
Q

How does sulfur oxide make acid rain?

A

1) S (s) + O2 (g) –> SO2 (g)
2) SO2 (g) + H2O (l) –> H2SO3 (aq)
3)2SO2 (g) + O2 (g) –> 2SO3 (g)
4)2SO3 (g) + H2O (l) –> H2SO4 (aq)

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70
Q

What is acid rain?

A

substance with a pH smaller than 5.6 (strong acids)

71
Q

What is rainwater?

A

substance that is naturally acidic due to the dissolved carbon dioxide

72
Q

How does nitrogen oxide make acid rain?

A

1) N2 (g) + O2 (g) –> 2NO (g)
2) N2 (g) + 2O2 (g) –> 2NO2 (g)
3) 2NO (g) + O2 (g) –> 2NO2 (g)
4) 2NO2 (g) + H2O (l) –> HNO2 (aq) + HNO3 (aq)
5) 2H2O (l) + 4NO2 (g) + O2 (g) –> 4HNO3 (aq)

73
Q

How does ocean acidification occur?

A

1) CO2 (g) + H2O (l) ⇌ H2CO3 (aq)
2) H2CO3 (aq) ⇌ H+ (aq) + HCO3- (aq)
3) HCO3- (aq) ⇌ H+ (aq) + CO32- (aq)

74
Q

What is an oxidation state?

A

number assigned to atoms to show the number of electrons transferred when forming a bond
- charge the atom would have if it was composed of ions

75
Q

What is oxidation?

A
  • increase in oxidation state
  • gain of oxygen
  • loss of hydrogen
  • loss of electrons
76
Q

What is reduction?

A
  • decrease in oxidation state
  • loss of oxygen
  • gain of hydrogen
  • gain of electrons
77
Q

What are the consequences of ocean acidification?

A
  • leads to higher ocean acidity near the surface of the ocean
  • inhibits shell growth in marine animals and causes coral bleaching
78
Q

What is an increase/decrease in oxidation?

A

increase = oxidation - electrons are lost (decreases in number)
decrease = reduction - electrons are gained (increase in number)

79
Q

What are the 10 rules for oxidation states?

A
  1. atoms in the form of elements have an oxidation state of 0
  2. simple ions have the same oxidation state as the charge of the ion
  3. in a compound, the total oxidation state must add up to 0
  4. oxidation states in a poly atomic ion adds up to the charge of the ion
  5. oxidation state is usually the same as the group number or valence electrons
  6. F has an oxidation state of -1 in all compounds as it is the most electronegative
  7. O has an oxidation state of -3 except in H2O2 where it is -1 and it is positive with Fl
  8. Cl has an oxidation state of -1, but is positive when bonded to O or Fl as it is less electronegative
  9. H has the oxidation state of +1 except when bonded to group 1 and 2 elements to form ionic hydrides
  10. oxidation states of transition metals in a complex ion can be worked out from the ligand charge
80
Q

How do you write ions and oxidation states?

A

oxidation state = charge –> number (-1)
ions = number –> charge (1-)

81
Q

Why are there discontinuities across period 4?

A
82
Q

How does it provide evidence for the existence of sub-levels?

A
83
Q

Where are transition metals located?

A
84
Q

What happens to atomic radius across period 4?

A
85
Q

Why can transition metals form alloys?

A
86
Q

What are physical properties of transition metals?

A
87
Q

Why is zinc not a transition metal?

A
88
Q

What are the magnetic properties of transition metals?

A
89
Q

What are chemical properties of transition metals?

A
90
Q

How can transition metals be used as catalysts?

A
91
Q

What is empirical and molecular formula?

A

empirical - simplest whole number ratio of atoms a compound contains
molecular - actual number of atoms in a molecule
M = (molar mass of empirical formula)n

92
Q

What is structural formula?

A

a representation of the molecule showing how atoms are bonded to each other

93
Q

What are the 3 types of structural formula?

A

-full structural formula
- condensed structural formula
- stereochemical formula

94
Q

What is a full structural formula?

A

shows every bond and atom
- uses 60, 90 or 180 angles as it is clearest, but this isn’t the true geometry

95
Q

What is a condensed structural formula?

A

groups atoms together and omits assumed C-H bonds to minimise information

96
Q

What is stereochemical formula?

A

3D model that shows the positions of atoms and groups around a central carbon atom

97
Q

What are limitations of the molecular formula?

A

properties of a compound are determined not only by the atoms it contains, but how they are arranged relative to each other and space

98
Q

What is skeletal formula?

A

shorthand respresentation of the structural formula showing all bonds and symbols except from C-H bonds
- C-C bonds are represented by offset lines and position and number of carbon atoms present are identified by the vertices where bond lines meet

99
Q

How can you find the number of hydrogen atoms attached?

A

subtract number of bonds drawn to the atom from 4

100
Q

What are aromatic compounds?

A

molecules with a benzene ring (C6H6)

101
Q

What is R?

A

any alkyl - C2H6 (CnH2n+1)

102
Q

What is unique about carbon and enables it to form more compounds than the sum of compounds formed by all the other elements?

A
103
Q

What are functional groups?

A

atoms or groups of atoms that are present in organic compounds that are responsible for a compounds physical properties and chemical reactivities

104
Q

What does saturated and unsaturated mean?

A

saturated - only contains single bonds
unsaturated - contains double or triple bonds

105
Q

What is a reaction pathway?

A

each step in a reaction involves a similar reactant from a previous product and involves a functional group interconversion in a series of discrete steps

106
Q

What makes up an amino acid?

A

amine group (NH3) and a carboxylic acid group (COOH)

107
Q

What happens during a condensation reaction between amino acids?

A

water is lost and a new bond is formed between the acid group of one amino acid and the amino group of another (peptide bond)

108
Q

What is a homologous series?

A

family of compounds in which each successive member differs by CH2 and can be described by a general formula

109
Q

What are trends in boiling points of homologous series?

A

boiling point increases with increasing carbon number due to increased intermolecular forces as molecular size increases

110
Q

Which IMF is affected?

A

LDF’s increase in strength but Hydrogen bonds don’t

111
Q

How can functional groups affect volatility?

A

most –> least volatile:
alkane, alkene, alkyne, halogenoalkane, aldehyde, ether, ester, ketone, alcohol, amine, amide, carboxylic acid

112
Q

How can functional groups affect the type of IMF present?

A

LDF –> Dipole-Dipole –> Hydrogen bonding:
alkane, alkene, alkyne, halogenoalkane, aldehyde, ether, ester, ketone, alcohol, amine, amide, carboxylic acid

113
Q

What is the IUPAC?

A

set of rules used by the International Union of Applied Chemistry to apply systematic names to organic and inorganic compounds

114
Q

What are the steps in naming compounds?

A
  1. Identify the stem - longest straight chain of carbon
    1. Identify the functional group - determines the suffix (ane for alkanes)
    2. Identify side chains - determines the prefix (methyl for CH3)
115
Q

How are esters formed?

A

when the alkyl group of an alcohol replaces the hydrogen in a carboxylic acid during a condensation reaction

116
Q

How are ethers formed?

A

two alkyl groups joined by an oxygen atom

117
Q

How do you name ethers?

A

Salts take the stem of the name (ethyl) and the alcohol forms the suffix (propanoate)

118
Q

How do you name esters?

A

Salts take the stem of the name (ethyl) and the alcohol forms the suffix (propanoate)

119
Q

What are structural isomers?

A

molecules that have the same molecular formula but different arrangements of the atoms so have different chemical and physical properties

120
Q

What are the properties of branched structural isomers?

A

the more branching present, the lower the melting point due to reduced surface contact which weakens the strength of the LDF’s between neighboring molecules (instantaneous and induced dipoles)

121
Q

What are the 4 types of structural isomers?

A
  • branched
  • unbranched
  • positional
  • functional group
122
Q

How are branched structural isomers used within the industry?

A

branched chain isomers burn more smoothly in internal combustion engines

  • factions with more branched chains are premium - higher octane number
123
Q

What are positional structural isomers?

A

isomers with the same molecular formula and functional group, but in a different position

124
Q

What are functional group structural isomers?

A

isomers with the same molecular formula but a different functional group

125
Q

What are primary compounds?

A

the C attached to the OH group is attached to 1 other C atom

126
Q

What are secondary compounds?

A

the C attached to the OH group is attached to 2 other C atoms

127
Q

What are tertiary compounds?

A

the C attached to the OH group is attached to 3 other C atoms

128
Q

What is mass spectroscopy?

A

Where a parent ion breaks down into smaller ions to create a fragmentation pattern which provides useful information about the mass of individual atoms (RAM) and the abundance of relative isotopes

129
Q

What can MS cause?

A

MS of organic compounds can cause fragmentation of the molecules

130
Q

What is a fragmentation pattern?

A

Provides evidence for the structure of a compound

131
Q

How do you work out the molecular ion using a graph?

A

Peak furthest to the right

132
Q

What charge are the peaks?

A

Peaks have to be a + charge, otherwise they would not be detected

133
Q

What happens to radicals?

A

Radicals aren’t +,so are not detected by the MS and disappear into the atmopshere

134
Q

What is IR spectra used for?

A

IR spectra can be used to identify the type of bond present in a molecule which can be determined by wavenumber and frequency

135
Q

What is wavenumber?

A

a frequency - number of waves per cm (cm-1)

136
Q

What are the numbers for infrared spectroscopy in terms of energy and wavelength, and frequency?

A

frequency - large
energy and wavelength - small

137
Q

What are ER waves?

A

electromagnetic waves are waves that transfer energy and carry information by interacting with substances in a different way

138
Q

How do x-rays interact with molecules?

A

x-rays have wavelengths similar to bond lengths in crystals which can be used to determine the crystal structure

139
Q

How does UV and visible light interact with molecules?

A

UV and visible light produce electronic transitions and tell us about energy levels in an atom

140
Q

How does IR radiation interact with molecules?

A

IR radiation is absorbed by bonds and causes them to stretch or bend in a specific way that tells us about the bond

141
Q

How do microwaves interact with molecules?

A

microwaves cause molecules to increase their rotational energy and tell us about bond lengths

142
Q

How do radio waves interact with molecules?

A

radiowaves can be absorbed by certain nuclei, causing them to reverse their nuclear spin, telling us about the hydrogen environments in a molecule

143
Q

What is the difference between when a simple or complex molecules when they vibrate?

A

simple - bond stretches
complex - bond stretches and bends

144
Q

What happens when bonds absorb IR?

A

either bend or stretch as the bonds in molecules become excited

145
Q

What does the natural frequency of a bond depend on?

A

a chemical bond can be though of as a spring; the natural frequency depends on:
- bond strength
- masses of atoms

146
Q

What are the 3 fundamental frequencies of water?

A
  • symmetric stretch (same direction)
  • asymmetric stretch (opposite direction)
  • symmetric bond
147
Q

What are the 4 modes of vibration?

A
  • inactive IR stretch (no change in dipole as molecule remains symmetrical)
  • asymmetric stretch (temporary dipole)
  • 2 symmetric bonds - into/out of the plane of the page (temporary dipole)
148
Q

How does mass of bond affect vibration?

A

larger mass - slower vibration due to weaker bond at lower frequency
smaller mass - faster vibration due to stronger bond at higher frequency

149
Q

How does number of bonds affect vibration?

A

more bonds - vibrate faster at higher frequencies
less bonds - vibrate slower at lower frequencies

150
Q

When will a bond interact with IR?

A

only polar bonds will absorb IR as the presence of separate partial - and + charges allow the electric field component of the EM to excite the vibrational energy of the molecule

151
Q

Why do symmetrical, non-polar bonds not absorb IR?

A

cannot interact with an electric field

152
Q

Which bonds are most common and why?

A

C-O / C–O / O-H / C-H
- absorb IR strongly

153
Q

What is the fingerprint region?

A

region that can be used to identify an unknown compound

154
Q

What are the regions from high to low wavenumber?

A
  • single bonds
  • triple bonds
  • double bonds
  • fingerprint region
155
Q

What is short and long wave radiation?

A

short - UV and visible light
long - IR

156
Q

What is the global warming potential?

A

compares the amount of IR energy absorbed by a gas compared to one tonne of CO2 over a certain period of time

157
Q

What is the greenhouse effect?

A

short-wave radiation is absorbed by the Earth’s surface and emitted as long-wave radiation which is absorbed by greenhouse gases and re-emitted back into the atmosphere, keeping the Earth warm

158
Q

What does the global warming potential depend on?

A
  • how effective the individual gas atoms are at absorbing IR
  • atmosphere lifetime of a gas
159
Q

What are the 3 fundamental frequencies of vibration for polyatomic atoms?

A
  • symmetric stretch
  • asymmetric stretch
  • symmetric bend
160
Q

What are the 4 modes of vibration for symmetric linear molecules?

A
  • symmetric stretch (IR inactive) - no change in dipole
  • asymmetric stretch (IR active) - temporary dipole
  • two symmetric bends (IR active) - temporary dipole as it bends away
161
Q

How do you work out the structure of a compound?

A
  1. Look at the IR spectra graphs
  2. Identify peaks and wavenumber
  3. Use data booklet to work out bonds present
162
Q

What is proton nuclear magnetic resonance spectroscopy? (HNMR)

A

gives information on the different chemical environments of hydrogen atoms in a molecule

163
Q

What is nuclear magnetic resonance spectroscopy?

A

used to find the structure and shape of molecules by identifying the different protons in a molecule which are bonded to different atoms

164
Q

What is MRI?

A

Uses NMR in the presence of a powerful magnet where radio waves are used to generate electrical signals which produce either 2D or 3D images.

165
Q

What 4 things can be deduced from HNMR?

A
  1. Number of peaks in the spectrum
  2. Position or chemical shift of each peak
  3. Size or integrated area of each peak
  4. Splitting pattern observed for each peak
166
Q

How does HNMR show different chemical environments?

A

Number of peaks observed in a spectrum = number of different chemical environments

167
Q

What is a chemical shift?

A

Position where a signal appears in a NMR spectrum measured in ppm

168
Q

What is the link between chemical shifts and the position of H atoms in a molecule?

A

Closer the atoms are to the OH group = higher chemical shift observed as the high electronegativity of O pulls electrons away from H, so nuclei become de-shielded and more susceptible to the effects of the external magnetic field.

169
Q

What does the area under the curve depend on?

A

Number of nuclei in the chemical environment

170
Q

What is an integrated trace?

A

shows the relative number of H atoms in an environment

171
Q

How can we determine the number of peaks caused by splitting?

A

n+1 where n is the number of neighbouring H atoms

172
Q

How is intensity of peaks determined?

A

follows Pascall’s triangle

173
Q

What else should be considered when analyzing NMR?

A
  • protons bonded to the same atom don’t interact with each other as they are equivalent and act as a group
  • protons on carbon atoms that are not next to each other do not interact with each other as the magnetic fields are too far apart to interact with spin-spin coupling
  • OH atoms don’t undergo spin-spin coupling with H of neighbour atoms as it isn’t split by other atoms.

chemistry (28 decks)

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