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Chemistry > DEFINITIONS > Flashcards

DEFINITIONS Flashcards

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1
Q

Relative Isotopic Mass

A

the mass of an atom of an isotope compared with 1/12th of the mass of an atom of carbon-12.

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2
Q

Relative Atomic Mass

A

is the weighted mean mass of an atom of an element compared with 1/12th of the mass of an atom of carbon-12.

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3
Q

general formula

A

the simplest algebraic formula of a member of a homologous series

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4
Q

Empirical Formula

A

the simplest whole number ratio of atoms of each element present in a compound

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5
Q

molecular formula

A

actual number of atoms of each element in a molecule

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6
Q

structural formula

A

minimal detail that shows the arrangement of atoms in a molecule in space

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7
Q

Homologous Series

A

a series of organic compounds containing the same functional group
with successive members differing by -CH2
.

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8
Q

carbocation

A

are positively charged carbon atoms with only three covalent bonds instead of four

  • primary - least stable - carbon with + charge attached to only one alkyl group
  • secondary
  • tertiary - most stable
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9
Q

radical

A

a species with an unpaired electron

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10
Q

orbital

A

region that can hold up to two electrons, with opposite spins

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11
Q

Ionic Bonding

A

an electrostatic attraction between positive and negative ions

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12
Q

Covalent bonding

A

the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

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13
Q

Dative covalent bond

A

a shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms only; also called a co-ordinate bond.

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14
Q

Electronegativity

A

the attraction of a bonded atom for the pair of electrons in a covalent bond.

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15
Q

First ionisation energy

A

the energy required to remove one electron from one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions.

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16
Q

Metallic bonding

A

strong electrostatic attraction between cations and delocalised electrons.

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17
Q

Disproportionation

A

is a redox reaction in which the same element is both oxidised and reduced.

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18
Q

Hess’s Law

A

the enthalpy change for a reaction that is independent of the route taken.

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19
Q

heterogenous catalyst

A

the catalyst is in a different phase to the reactants

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20
Q

homogenous catalyst

A

the catalyst is in the same phase as the reactants

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21
Q

Adsorption

A

where something sticks to a surface
- One or more of the reactants are adsorbed on to the surface of the catalyst at active sites.

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22
Q

electrophile

A

electron pair acceptor

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23
Q

nucleophile

A

electron pair donor

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24
Q

Structural isomers

A

compounds that have the same molecular formula but different structural formulae

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25
Q

Stereoisomers

A

compounds with the same structural formula but a different arrangement in space.

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26
Q

Brønsted Lowry base

A

species that accepts a proton

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27
Q

Brønsted Lowry acid

A

species that donates a proton

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28
Q

Buffer solution

A

a system that minimises pH changes when small amounts of an acid or a base are added

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29
Q

Pi bond
π

A

A bond formed by the sideways overlap of p orbitals with the electron density above and below the sigma bond.

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30
Q

Sigma bond
σ

A

A bond formed by the overlap of each bonding atom consisting of two electrons and with the electron density centred around a line directly between the nuclei of the two atoms.

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31
Q

E/Z isomerism

A

a type of stereoisomerism caused by the restricted rotation of π bonds. Two
different groups must be attached to each carbon atom of the C=C group

E = opposite so like \ or /
Z = same like _ or -

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32
Q

cis-trans isomerism

A

type of E/Z isomerism in which the two substituent groups attached
to the cabon atoms are the same

cis = opposite so / or \
trans = same so _ or -

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33
Q

average bond enthalpy

A

Breaking of one mole of bonds
In gaseous molecules

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34
Q

Enthalpy change of combustion

A

enthalpy change when one mole of a substance reacts completely with oxygen under standard conditions and standard states

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35
Q

Enthalpy change of neutralisation

A

nthalpy change that accompanies the reaction of an acid by a base to form one mole of water under standard conditions and standard states

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36
Q

Enthalpy change of formation

A

enthalpy change when one mole of a compound is formed from its element under standard conditions and standard states

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37
Q

Enthalpy change of solution

A

the enthalpy change when one mole of a solute dissolves in a solvent under standard conditions.

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38
Q

Enthalpy change of hydration

A

the enthalpy change when the separate gaseous ions interact with polar water molecules to form hydrated aqueous ions

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39
Q

Lattice enthalpy

A

enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions

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40
Q

Entropy

A

measure of the dispersal of energy in a system which is greater, the more disordered a system.

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41
Q

Spontaneous

A

energetically feasible (i.e. whether the reaction is able to happen i.e. delta G < 0)

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42
Q

Oxidising agent

A

takes electrons from the species being oxidised, it contains the species being reduced.

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43
Q

Reducing agent

A

adds electrons to the species being reduced, the reducing agent contains the species that is being oxidised

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44
Q

Polar bond

A

covalent bond in which there is an unequal share of the electrons between the 2 atoms due to the differing electronegativities of the atoms involved. One atom will have a partial positive charge while the other will have a partial negative charge.

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45
Q

Aromatic

A

organic compound with benzene ring

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46
Q

Dipole

A

partial charge on an atom which is caused by the differing electronegativities of
atoms in a covalent bond.

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47
Q

Alicyclic

A

an aliphatic compound that is arranged in non-aromatic rings (with or without side
chains)

48
Q

Aliphatic

A

a compound containing carbon and hydrogen atoms joined in straight or branched
chains or in non-aromatic rings.

49
Q

Heterolytic Fission

A

when a covalent bond breaks, one bonding atom receives both electrons from the bonded pair

  • different products +ve ion and one -ve ion
50
Q

homolytic fission

A

each of the covalently bonded atoms takes one of the shared electrons, forms 2 radicals

  • same products
51
Q

Le Chatelier’s Principal

A

if a system at equilibrium is subjected to a small change, the equilibrium tends to shift so as to minimise the effect of the change

52
Q

chiral centre

A

an atom which is bonded to four different substituents / groups

53
Q

optical isomers

A
  • octahedral
  • bidentate ligand
  • non superimosable mirror images
54
Q

Test for Alkene

A

Use bromine water
+ = decolourises brown to clear duh

55
Q

Test for halide ions

A

use AgNO3 and ethanol
positive test:
colourless (no ppt) - F-
white ppt = Cl-
Cream ppt = Br-
Yellow ppt = I-
children will cry yearly

56
Q

Test for Carbonyl

C=O and 2 R group of C

A

Use Brady’s reagent
+ = yellow/orange ppt

57
Q

Test for Aldehyde and ketone

aka fehlings solution

A

add 2-4 dinitrophenylhydrazine
+ = blue solution to red ppt shows aldehyde or ketone present C=O present

58
Q

Test for Aldehyde

H - C = O and R group of C

A

use Tollens reagent
+ = silver mirror
- = ketone has no change

59
Q

Test for Carboxylic acid

HO- C = O and R group of C

A

Use sodium carbonate and test gas for limewater
+ = bubbling and white ppt formed with limewater

60
Q

Test for Alcohol

A

Use potassium dichromate
+ = orange to green IF primary alcohol
- = no change as tertiary alcohol

61
Q

Test for ammonium ions

A

use sodium hydroxide solution dropwise and gently heat then use red litmus paper
+ = red litmus turns blue

62
Q

Test for transition metal ions

A

use aq ammonia or sodium hydroxide dropwise
Cu(II) = turns blue ppt
Fe(II) or Cr(III) = turns green ppt
Mn(II) = turns brown ppt

63
Q

Test for sulfate ions

A

add dilute HCl then barium chloride
+ = white ppt formed

64
Q

Test for carbonate

do this FIRST

A

add dilute HNO3 and + test is bubbling

65
Q

NO radicacls catalyse breakdown of ozone

A

Propogation step 1:
NO● + O₃ ➜ NO₂● + O₂

Propogation step 2:
NO₂● + O ➜ NO + O₂

66
Q

K<1

A

indicates that there are more reactants than products at equilibrium

67
Q

k>1

A

indicates that there are more products than reactants at equilibrium

68
Q

K=1

A

neither reactants nor products are favored

the concentration of reactants and of products are equal at equilibrium

69
Q

bidentate ligand

A

2 lone pairs are donated to form 2 dative covalent bonds

70
Q

coordination number

A

the number of dative covalent bonds formed between ligands and a metal ion centre

71
Q

Why is Sc and Zn not transition elements?

A
  • transition elelements have an ion with an partially-filled d sub-shell
  • so Sc and Zn are not transition elements
  • Sc3+ = 1s2 2s2 2p6 3s2 3p6
    Zn2+ = 1s2 2s2 2p6 3s2 3p6 3d10
  • Sc3+ d sub-shell empty
  • Zn2+ d sub-shell full
72
Q

Optical isomers

A
  • octahedral
  • bidentate ligands
  • non superimposable mirror images
73
Q

How does lig sub allow haemoglibin to transport oxygen in blood?

A

O2/oxygen bonds to Fe2+/Fe(II)
(When required,) O2 substituted OR O2 released

74
Q

In the presence of carbon monoxide, less oxygen is transported in the blood.
Suggest why, in terms of bond strength and stability constants.

A
  • Stability constant value with CO is greater than with
    complex in O2
  • CO has greater affinity for ion/metal/haemoglobin
75
Q

Config of Nickel

A

1s2 2s2 2p6 3s2 3p6 3d8 4s2

76
Q

config of chromium

A

1s2 2s2 2p6 3s2 3p6 3d5 4s1

77
Q

config of copper

A

1s2 2s2 2p6 3s2 3p6 3d10 4s1

78
Q

disproportionation reaction

Chlorine and treating water

A

Cl2 + H2O –> HCl + HClO

Cl2 = 0 and HCL = -1 and HClO = +1

79
Q

disproportionation reaction

Chlorine and cold dilute AQ NaOH

BLEACH!!!

A

Cl2 + 2NaOH –> NaCl + NaClO + H2O
ionic= Cl2 + 2OH- –> Cl- + ClO- + H2O

cl2 = 0 and cl- = -1 clo- = +1

80
Q

At room temperature and pressure, the first four members of the alcohol homologous series are liquids whereas the first four members of the alkanes homologous series are
gases.

A
  • Alkanes have london forces
  • Alcohols have hydrogen bonds and london
  • Hydrogen bonds are stronger
81
Q

A proposed mechanism for this reaction takes place in several steps. Suggest two reasons why it is unlikely that this reaction could take place in one ste

A
  • rate eq does not match in overall eq
  • collision unlikely to happen with more than 2 species
82
Q

A small amount of aqueous ammonia, NH3(aq), is added to the buffer solution. Explain, in terms of equilibrium, how the buffer solution would respond to the added NH3(aq).

A
  • NH3 reacts with H+ of acid forming NH4+ and so EQ shifts in opposite direction to form more H+
83
Q

Properties of a transition element

A
  • forms voloured compounds
  • has diff oxidation states
  • elements and compounds used as catalysts
  • element forms AT LEAST 1 stable ion with a partially filled d sub shell
84
Q

[Cu(H₂O)₆]²⁺

A

Pale blue solution

85
Q

[Cu(H₂O)₆]²⁺ + weak dilute NaOH

A

Pale blue ppt

[Cu(H₂O)₆]²⁺ + 2OH- –>[Cu(H2O)4(OH)2] + 2H2O

86
Q

[Cu(H₂O)₆]²⁺ + weak NH₃

A

Pale blue ppt

[Cu(H₂O)₆]²⁺ + 2NH- –>[Cu(H2O)4(OH)2] + 2NH4+

87
Q

[Cu(H₂O)₆]²⁺ + excess NH₃

A

Dark blue solution

[Cu(H₂O)₆]²⁺ + 4NH3 –>[Cu(NH3)4(H2O)2]2+ + 4H2O

88
Q

Ammonia acts as what before a ligand

A

BASE

89
Q

[Cu(H₂O)₆]²⁺ + conc HCl

A

Yellow Solution

[Cu(H₂O)₆]²⁺ + 4CL– –>[CuCl4]2- + 6H2O

90
Q

[Fe(H₂O)₆]³⁺

A

Yellow solution

91
Q

[Fe(H₂O)₆]³⁺ + weak dilute NaOH

A

Brown ppt

[Fe(H₂O)₆]³⁺ + 3OH- –> [Fe(H2O)3(OH)3] +3H2O

92
Q

[Fe(H₂O)₆]³⁺ + weak NH₃

A

Brown ppt

[Fe(H₂O)₆]³⁺ + 3NH3 –> [Fe(H2O)3(OH)3] +3NH4+

93
Q

[Fe(H₂O)₆]²⁺

A

Pale Green solution

94
Q

[Fe(H₂O)₆]²⁺ + weak dilute NaOH

A

Dark green ppt

[Fe(H₂O)₆]²⁺ +2OH- –> [Fe(H2O)4(OH)2] +2H2O

95
Q

[Fe(H₂O)₆]²⁺ + weak NH₃

A

Dark green ppt

[Fe(H₂O)₆]²⁺ +2NH3- –> [Fe(H2O)4(OH)2] +2NH4+

96
Q

[Mn(H₂O)₆]²⁺

A

Pale pink solution

97
Q

[Mn(H₂O)₆]²⁺ + weak dilute NaOH

A

Pale brown ppt

[Mn(H₂O)₆]²⁺ +2OH- –> [Mn(H2O)4(OH)2] + 2H2O

98
Q

[Mn(H₂O)₆]²⁺ + weak NH₃

A

Pale brown ppt

[Mn(H₂O)₆]²⁺ +2NH3 –> [Mn(H2O)4(OH)2] + 2NH4+

99
Q

[Cr(H₂O)₆]³⁺

A

Violet solution

100
Q

[Cr(H₂O)₆]³⁺ + weak dilute NaOH

A

Dark green ppt

[Cr(H₂O)₆]³⁺ + 3OH- –> [Cr(H2O)3(OH)3] + 3H2O

101
Q

[Cr(H₂O)₆]³⁺ + excess NaOH

A

Dark green solution

[Cr(H₂O)₆]³⁺ + 6OH- –> [Cr(OH)6]3- + 6H2O

102
Q

[Cr(H₂O)₆]³⁺ + weak NH₃

A

Dark green ppt

[Cr(H₂O)₆]³⁺ + 3NH3 –> [Cr(H2O)3(OH)3] + 3NH4+

103
Q

[Cr(H₂O)₆]³⁺ + excess NH₃

A

Purple solution

[Cr(H₂O)₆]³⁺ + 6NH3 –> [Cr(NH3)6]3+ + 6H2O

104
Q

Ti

A

+3 = purple

105
Q

V

A

+2 = purple
+3 = green
+4 = blue
+5 = yellow

106
Q

Cr

A

+2 = blue
+3 = green
+6 = orange

107
Q

Mn

A

+2 = pink
+4 = dark pink
+6 = green
+7 = purple

108
Q

Co

A

+3 = green

109
Q

Ni

A

+2 = green

110
Q

does pH of a buffer solution change

A
  • pH stays same
  • ratio of [HA]/[A-] is same
111
Q

standard conditions for electrode potential

A

298k or 25 degrees
1mol dm^-3

112
Q

which equation do u flip when making an overall eq for electrode potential eq

A

THE LESS POSITIVE ONE XOXO

113
Q

Strongest reducing agent

A
  • the one being oxidised
  • most negative cell potential
114
Q

Healthy human blood needs to be maintained at a pH of 7.40 for the body to function normally.
Carbonic acid, H2CO3, is a weak acid which, together with hydrogencarbonate ions, HCO3 acts as a buffer to maintain the pH of blood.
The pKa value for the dissociation of carbonic acid is 6.38.
Explain, in terms of equilibrium, how the carbonic acid–hydrogencarbonate mixture acts as a
buffer in the control of blood pH, and calculate the [HCO3−] : [H2CO3] ratio in healthy blood

6 marks

A

H2CO3(aq) ⇌ H+(aq) + HCO3-(aq)
* Addition of H+ causes ⇌ to shift to left
* Addition of OH– causes ⇌ to shift to right

When increasing H+ it will react with HCO3-
When increasing OH- it will react with H2CO3

work out ratio !!

115
Q

Red blood cells contain haemoglobin.
Explain using ligand substitutions:
* how haemoglobin transports oxygen around the body
* why carbon monoxide is toxic.

3 marks

A
  • O2 binds with Fe2+ in haemoglobin
  • it is replaced y H2O or CO2 when required
  • CO forms a stronger biond than O2 so CO toxic

Chemistry (9 decks)

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