Chemistry 2 Flashcards
(112 cards)
1
Q
Elements are composed of atoms which may be linked to form
A
molecules
2
Q
relative atomic mass Ar
A
the mass of 1 atom relative to 1/12 the mass of 1 atom of carbon-12
carbon-12 is the most common isotope of carbon and its mass is 12
3
Q
Relative MOLECULAR mass Mr definition
A
-the mass of 1 molecule of an element or compound compared with 1/12th the mass of 1 atom of carbon-12
4
Q
Relative MOLECULAR mass Mr HOW TO CALCULATE
A
addition of Ar atoms in molecule
5
Q
the mole
A
A mole of carbon 12 Is the amount of chemical which contains exactly 12g of 12C
6
Q
The Avogadro constant and what it is
A
12 /1.9926 x 10^-23 =6.022 x 10^23
1.9 is the mass of one atom
7
Q
number of moles =
A
mass of 1 substance/mass of 1 mole (g)
8
Q
molarity of solutions
A
the amount of solute in moles in 1 dm^3 of solution
9
Q
calculating molarity of solutions
A
-convert to dm^3 for example if 10cm of 0.1 then 10/1000 x 0.1 is how many in dm^3
-then multiply by Mr
10
Q
A large Kc value indicates
A
the product concentration is high and the forward reaction is favoured.
11
Q
le chetiliers
A
poster
12
Q
haber process
A
iron can be used as catalyst
13
Q
weak acids and bases only
A
partially dissolve in water
14
Q
The pH of a weak acid depends on two factors
A
-the concentration of the acid
-its pKa value (pKa = -log10 Ka)
15
Q
to calculate the pH of weak acids …
A
-use the Ka formula to find concentration of [H]
-then put in log formula
16
Q
strong bases
A
-fully ionised
-concentration of hydroxide (OH-) is equal to the concentration of the base
17
Q
weak bases
A
-only partially ionised
-equlibrium is established
18
Q
aqueous ammonia is the most common
A
weak base
19
Q
the base ionisation constant
A
Kb = [BH+]
look at slide 14 on Acids and bases part 2
20
Q
Henderson-hasselbalch equation
A
-possible to calculate the pH of a buffer solution
pH = pKa + log10 ([base]/[acid])
21
Q
acid =
A
a substance which contains hydrogen and releases hydrogen ions (H+) when dissolved in water
22
Q
base =
A
substance which reacts with an acid to form a salt plus water
23
Q
acid is proton
A
donor
24
Q
base is proton
A
acceptor
25
acid + base =
salt + water
26
how the atom arose
look on ppt atomic structure
27
atomic number
equal to the number of positive charges or protons in the atom
bottom left
28
labelled numbers
-atomic mass top = protons + neutrons
atomic number = protons + electrons unless isotope
29
if the atomic mass is different
number of neutrons changes
30
the 1st ionisation energy
defined as the energy required to turn 1 mole of an element in the gas state into 1 mole of its ions
31
patterns in ionisation energy increasing in reactivity across the periodic table
as you go up the table increase in charge and attraction
32
isotopes are elements containing atoms with the same
atomic number
but different atomic mass
they can be radioactive
33
intra molecular bonds
ionic
covalent
34
inter-molecular bonds
dispersion
35
a vertical column called a group contains elements with
similar chemical properties due to same number of valence electrons
36
horizontal row is called a
period
atomic number increases from left to right along the row
37
groups
-have same number of outer shell electrons
-down a group = increasing number of electron shells
-melting and boiling points decreases in groups 1 to 4 and increase In groups 5 to 8
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atoms become larger
-group 1 and 2 elements become more reactive
-groups 6 and 7 elements become less
39
within periods they have the same number of electron
shells
40
across a period
-elements become more electronegative
-atomic radius decreases
-melting and boiling points rise to a peak (group 4) then fall
41
electronegativity increases across the periodic table
across and up
42
after passing an electron from the metal to non both adopt a
noble gas configuration
43
ionic bonding requires electron
transfer
44
another example of ionic bonds
ionic bonds can be pH sensitive and not all ionic bonds can be removed by electrolysis
45
covalent bonding
-incomplete electron transfer leads to a shared electron noble gas configuration
each atom donates an equal number of electrons
46
coordinate bonding
sharing electrons only supplied by one side
47
metallic bonding
-metal elements can share their outer electrons
48
to infer a structure
notice the electrons in the outer electron shell
-repulsion axis
49
intermolecular forces
-hydrogen bonds, electrostatic bonds
-van der Waals bonds and teh hydrophobic exclusion
50
intermolecular forces strings of interactions in order
-covalent bond
-ionic
-hydrogen
-van der waals
51
dotted line
hydrogen bond
52
filled in line
covalent
53
electrostatic dispersion bonds
-dipole-dipole
-dipole-ion
beyond the hydrogen
54
molecular orbitals
shapes of molecules explained by atomic and molecular orbital theory
55
Stereochemical formulae different lines mean
-solid line
bond in the plane of the paper
56
Stereochemical formulae different lines mean
-dashed line/diminishing wedge or a striped wedge
bond that goes behind the paper
57
Stereochemical formulae different lines mean
-enlarging wedge
bond that goes in front of the paper
58
a single line represents
single covalent bond
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the ends of all bonds are occupied by
a hydrogen atom
60
saturated molecules
contain single c - c bonds
61
Alkane formula
Cn H(2n +2)
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Fractional distillation
different fractions obtained by fractional distillation crude oil
63
catalytic cracking
of longer chain alkanes is carried out as a means of increasing the yield of the petrol fraction obtained in fractional distillation
64
double bonds
made up of two electron pairs
65
Alkenes
contain one c to c double bond these carbon atoms are sp^2 hybridised
66
ethene no rotation around
the c= c bond
67
alkene different structures on ppt
organic 1 FA slide 26
68
Alkynes
ethyne has a title bond and formula C2H2
69
aldehydes and ketones
both carbonyl compounds
70
Aldehydes are easily oxidised to
carboxylic acids
71
esters
produced by mixing together an acid and an alcohol
72
triglycerides and fat
made by esterification of glycerol a special type of alcohol with three fatty acids
glycerol forms polar head of these special esters
three fatty acids with long alkane chains join this to form saturated fats
73
trans-fats have one or more
double bonds in their fatty acids which allow each of the side chains to line up parallel so they pack well
74
cis-fats
have tails sticking out at angle so poorer packing results in lower melting point
75
naming the molecules ppt
in organic 1 on page 37
76
Alkanes
unreactive non-polar hydrocarbons
-strong c-c bonds
-no dipole to attract charged molecules
reactions restricted
-combustion
-substituition reactions in which they rely on highly reactive free radicals
77
Alkenes
-much more reactive than alkanes
-due to presence of double bond
-unsaturated alkenes turn to saturated molecules following addition reactions
78
electron rich pi bond attracts
molecules with sigma+ charge
79
benzene and electrophilic substituition
-instead of electrophilic addition reactions benzene undergoes electrophilic substituition
-positive ion or group of atoms is attracted to the pi electron cloud
-H atom removed
80
Alcohol general formula
CnH2n+1 - OH
81
primary alcohol
has 2 hydrogen atoms attached to the carbon atom OH group
82
secondary alcohol
has 1 hydrogen atom attached to the carbon atom that bears the OH group
83
tertiary alcohols
no single hydrogen atoms on the carbon atom that bears the OH group
84
oxidation of alcohols
strong oxidising agent required in a reaction that can be used in breathalyser tests for ethanol
85
oxidation of ethanol to ___ then to
ethanal then to ethanoic acid
86
carbonyl compounds the two main types
aldehydes and ketones
87
aldehydes vs ketones
oxidised by weak oxidising agents such as Benedict's reagent to carboxylic acids
-blue copper two ions are reduced to a brick red copper oxide precipitate
-ketones do not reduce benedicts
-glucose has aldehyde groups so acts as a reducing sugar on benedicts
88
the carbonyl group is attractive to
nucleophiles
89
carboxylic acids
-soluble in water
-form h bonds between two acid molecules or between acid molecules and water
-do not dissociate completely therefore ARE WEAK ACIDS
90
fats are
triesters
91
prostaglandins
-affect many physiological processes
-act as hormones or hormone modulatirs
-derived from C20 fatty acids with at least three double bonds
92
spectrometry look on
ppts
93
IR spectroscopy
-radiation across range is passed through substance
-strong bonds = low mass atoms vibrate and absorb energy at high frequencies
-weak bonds = high atomic masses absorb at low frequencies
94
what can IR spectroscopy tell us
-used to identify and differentiate between species of bacteria
-show conversion of prion protein into misfiled pathological form
95
Atomic emission spectroscopy
-atomic emission spectroscopy (ICP_AES)
-aerosolised sample is carried into argon gas plasma
-radiation emitted as atoms return to lower energy levels
96
nuclear magnetic reasoning
-atomic nuclei with odd mass numbers such as hydrogen, posses a spin which can align with or against an applied magnetic field
97
UV/visible spectroscopy
-used to detect electronic transistions between molecular energy levels
-group of atoms producing a characteristic absorption called a chromophore
98
beer-lambert law
A = E x C x L
aborbance
mlar absorptivity Lmol-1cm-1 (extinction coefficient)
concentration L-1
path length cm
99
UV/visible spectroscopy
-spectra result from electronic transitions between molecular energy levels
-molecular orbitals represent different quantised energy levels for molecules in the same way as atomic orbitals do for atoms
100
type of electron transitions
-sigma
represent valence bonds which have the lowest energy levels
101
type of electron transitions
-pi
pi bonds are at a higher energy level
102
type of electron transitions
-non bonding electrons
N, O Halogen or S
which do not participate in bonding occupy the highest energy ground state
103
benzene rings
have delocalised electrons as do heterocyclic rings with carbon and nitrogen
104
beta carotene
conjugated because of its alternating double and single bonds this decreases the energy needed for a pi-pi* transition
shifting to a longer visible wavelength
105
what do we use UV for?
-locating samples in purification process
-checking concentration of product
-changes in conformation of proteins/protein
-enzyme actvity
106
types of isomerism
-structural or stereoisomerism
107
structural isomerism
simply molecules with different structural formulae
-branched chains
-position of functional groups
-different functional groups
108
steroisomerism
-same structural formulae the orientation of bonds is different
-geometric isomerism
-optical isomerism
109
chain isomers
chan molecules can have varying amounts of branches
110
positional isomers
functional groups can adopt several different positions
111
E/Z isomerism
special case of geometric isomerism when you have 4 different groups around the double bond
-if highest rank groups are together = Z
-opposite = E
112
D and L amino acids
- POSITIVE enantiomers can also be described as d enantiomers (right handed clockwise)
- NEGATIVE enantiomers can also be described as L enantiomers (left handed anti-clockwise)
