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Higher Chemistry 2016 > Prelim revision (Unit 1,2 and 3A) > Flashcards

Prelim revision (Unit 1,2 and 3A) Flashcards

1
Q

What is the definition of activation energy?

A

The energy required by colliding molecules to form an activated complex

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2
Q

What is the definition of the bonding continuum?

A

A concept applied to bonding. Ionic and covalent bonding lie at opposite ends of the bonding continuum with polar covalent bonding in between.

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3
Q

What is the definition of collision geometry?

A

A term used to describe the way reactants collide with each other

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4
Q

What is the definition of collision theory?

A

A theory used to explain the factors which lead to a successful reaction. It explains how altering variables can affect the speed of reaction.

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5
Q

What does collision theory require reactants to do?

A

Collide, have the correct collision geometry and have a minimum energy (the activation energy) before a reaction occurs.

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6
Q

What is the definition of covalent atomic radius?

A

A measure of atomic size, being half the distance between the nuclei of two covalently-bonded atoms of an element. Covalent bond lengths between any two atoms can be obtained by adding the appropriate covalent atomic radii.

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7
Q

What is the definition of covalent bonding?

A

Bond formed between two atoms by the sharing of a pair of electrons. Usually occurs with non metal atoms

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8
Q

What is the definition of a covalent network?

A

A very strong and stable structure formed by certain elements and certain compounds. All the atoms are held together by strong covalent bonds.

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9
Q

What are characteristics of covalent networks?

A

Covalent network compounds are all solids at room temperature and have very high melting points.

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10
Q

What is the definition of delocalised electrons?

A

Electrons which are not confined to a single orbital between a pair of atoms. Delocalised electrons are free to move away from the atom they came from.

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11
Q

What is the definition of an electron?

A

A particle that moves around the nucleus of an atom. It had a single negative charge but it’s mass is negligible compared with that of a proton or neutron.

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12
Q

What is the definition of electronegativity?

A

The strength of attraction by an atom of an element for its bonding electrons.

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13
Q

What is the definition of an endothermic reaction?

A

A reaction in which heat energy is absorbed from the surroundings. It has a positive enthalpy change

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14
Q

What is the definition it an exothermic reaction?

A

A reaction in which heat energy is released to the surroundings. It has a negative enthalpy change

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15
Q

What is the definition of group?

A

A column of elements in the Periodic Table

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16
Q

What is the definition of intermolecular bonds?

A

Bonds between molecules.They are much weaker than intramolecular bonds

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17
Q

What is the definition of intramolecular bonds?

A

Bonds within molecules

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18
Q

What is the definition of a covalent bond?

A

Bond formed as a result of attraction between positive and negative ions

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19
Q

What is the definition of ionisation?

A

The loss or gain of electrons by neutral atoms to form ions

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20
Q

What is the definition of ions?

A

Atoms or groups of atoms that possess a positive or negative charge due to loss or gain of electrons

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21
Q

What is the definition of a lattice?

A

The 3D arrangement of positive and negative ions in the solid, crystalline state of ionic compounds.

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22
Q

What is the definition of London dispersion forces?

A

The weak forces of attractions between all atoms and molecules, caused by temporary dipoles

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23
Q

What is the definition of metallic bonding?

A

The bonding responsible for typical metallic properties. Each atom loses its outer electrons to form positive ions

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24
Q

How are ions packed in metallic bonding?

A

The ions pack together in a regular crystalline arrangement with the electrons delocalised through the structure, binding the ions together

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25
Q

Name 3 examples of metallic properties?

A

Malleability, ductility and electrical conductivity in metals and alloys

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26
Q

What is the definition of monatomic?

A

A term used to describe the noble gases since they are composed of individual atoms which do not bond to each other. They are held together by London dispersion forces in the liquid and solid state

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27
Q

What is the definition of a non-polar covalent bond?

A

A covalent bond where both atoms share the electrons weakly

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28
Q

Where does non-polar covalent bonding occur?

A

Between all elements that exist as molecules, since the atoms joining are identical. It also occurs in compounds where the bonding atoms have a small difference in electronegativity

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29
Q

What is the definition of nucleus?

A

The extremely small centre of an atom

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30
Q

What is found in the nucleus of an atom?

A

Neutrons and protons

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31
Q

What is the definition of permanent dipole-permanent dipole interactions?

A

The attraction between molecules which possess a permanent dipole because of the presence of polar bonds

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32
Q

What is the definition of polar covalent bonds?

A

Bonds formed between non-metallic atoms by sharing a pair of electrons. If the atoms have considerably different electronegativities, the electrons are not shared equally, the more electronegative atoms becoming slightly negative in comparison with the other atom. As a result it is non-polar

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33
Q

What is the definition of an activated complex?

A

An unstable arrangement of atoms formed at the maximum of the potential energy barrier during a reaction

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34
Q

What is the definition of alkanals?

A

A homologous series of aldehydes

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35
Q

What is the general formula for alkanals?

A

C (n) H(2n) O

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36
Q

What is the definition of alkanes?

A

A homologous series of saturated hydrocarbons eg methane

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37
Q

What is the general formula for alkanes?

A

C (n) H (2n + 2)

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38
Q

What is the definition of alkanoic acids?

A

A homologous series of carboxylic acids

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39
Q

What is the general formula for alkanoic acids?

A

C (n) H (2n) O (2)

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40
Q

What is the definition of alkanols?

A

A homologous series of alcohols

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41
Q

What is the general formula for alkanols?

A

C (n) H (2n + 1) OH

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42
Q

What is the definition of alkanones?

A

A homologous series of ketones

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43
Q

What is the general formula for alkanones?

A

C (n) H (2n) O eg. propanone

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44
Q

What is the definition of alkanes?

A

A homologous series of unsaturated hydrocarbons. Each member contains a carbon-carbon double bond

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45
Q

What is the definition of an alkyl group?

A

A group of carbon and hydrogen atoms forming a branch in a carbon compound

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46
Q

What is the definition of an amide link?

A

Group of atoms formed by the condensation polymerisation of amino acids in the formation of protein chains. The amide link is -CO-NH- and occurs between each pair of amino acid residues in the chain.

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47
Q

What is the definition of amino acids?

A

Compounds of general formula, H2NCHRCOOH, which link by condensation reaction to form proteins.

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48
Q

What is the definition of an antioxidant?

A

Compounds that slow oxidation reactions

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49
Q

What is the definition of a carbonyl group?

A

The functional group present in ketones, C=O

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50
Q

What is the definition of a carboxyl group?

A

The functional group present in carboxylic acids, -COOH.

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51
Q

Where does name for a carboxylic group derive from?

A

The name derives from the fact that the carboxyl group contain a carbonyl and hydroxyl group

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52
Q

What is the definition of emulsion?

A

A mixture of liquids where small droplets of one liquid are dispersed into another liquid.

53
Q

What is the definition of essential amino acids?

A

Amino acids that cannot be made by the body and need to be obtained through diet.

54
Q

What is the definition of fatty acids?

A

Carboxylic acids formed from the hydrolysis of days and oils

55
Q

What is the definition of glycerol?

A

Propan-1,2,3-triol

56
Q

How is glycerol formed?

A

From the hydrolysis of fats and oils

57
Q

What is the definition of hardening?

A

The process of hydrogenating an oil to produce a more solid compound

58
Q

What is the definition of hydration?

A

The addition of water to an unsaturated compound

59
Q

What is the definition of hydrogenation?

A

The addition of hydrogen to an unsaturated compound.

60
Q

What is the definition of hydrolysis?

A

The breaking down of larger molecules into smaller molecules by the reaction of water

61
Q

What is the definition of hydrophilic?

A

A term used to describe molecules, or parts of a molecule, which are attracted to water.

62
Q

What is the definition of hydrophobic?

A

A term used to describe molecules, or parts of a molecule, which repeal water and will not bond to water.

63
Q

What is the definition of miscibility?

A

The ability of liquids to mix perfectly together

64
Q

What is the definition of oils?

A

Esters formed from one mole of glycerol and three molecules of (usually unsaturated) carboxylic acids.

65
Q

What is the definition of fats?

A

Esters formed from one molecule of glycerol and three molecules of (usually unsaturated) long-chain carboxylic acids.

66
Q

What is the definition of oxidation?

A

A process in which electrons are lost

67
Q

What is the definition of oxidising agent?

A

A substance that gains electrons, in other words is an electron acceptor.

68
Q

What is the definition of a reducing agent?

A

A substance that loses electrons,in other words is an electron donor

69
Q

What is the definition of a saturated hydrocarbon?

A

A hydrocarbon in which all carbon-carbon covalent bonds are single bonds

70
Q

What is the definition of soaps?

A

Salts of fatty acids, e.g. sodium stearate. Soaps have an ionic head that is water soluble and a covalent tail that is soluble in oil.

71
Q

What is the definition of a triglyceride and how are they formed?

A

The molecules found in fats and oils. They are formed from one glycerol molecule joining to three fatty acid molecules

72
Q

What is the definition of unsaturated compounds?

A

Compounds in which there are carbon-carbon double or triple bonds.

73
Q

What is the definition of alcohols?

A

Carbon compounds which contain the hydroxyl functional group, -OH

74
Q

What is the process of making an ester known as?

A

A condensation reaction

75
Q

What are some uses of esters?

A

Solvents, flavourings or perfumes

76
Q

What happens when oils are tested with bromine water?

A

Shaking of oils with bromine water results in the bromine water being rapidly decolourised, with bromine a decolourisation being the standard test for unsaturation

77
Q

What is the only chemical difference between fats and oils?

A

Oils contain many more double bonds

78
Q

How can hardening of oils be carried out?

A

By the addition of hydrogen across the double bonds

79
Q

Why do fats and oils not dissolve in water?

A

Because they are non-polar. The long hydrocarbon chains cannot bond to water and there are no polar -OH groups or ions that can bond to water

80
Q

How are soaps derived?

A

From fats or oils by treating them with an alkali such as sodium hydroxide or potassium hydroxide. This results in alkaline hydrolysis of the three ester links in the fat or oil, and produces glycerol and the salt of the fatty acids. These salts are ‘soap’

81
Q

Why are fats and oils an essential part of the human diet?

A

Fats and oils are used in our diets to provide us with energy. They play an important role in the transport of vitamins which are soluble in fats around the human body.

82
Q

What do precipitates do?

A

The precipitates reduce the cleansing action of soap and build up to leave a ‘scum’ around baths etc

83
Q

How are aldehydes formed?

A

They are formed by oxidation of primary alcohols

84
Q

What functional group do aldehydes contain?

A

-CHO functional group

85
Q

What do aldehydes oxidise to produce?

A

Carboxylic acids

86
Q

What when oxidised produces an aldehyde?

A

A primary alcohol

87
Q

What when oxidised produces a ketone?

A

A secondary alcohol

88
Q

What do tertiary alcohols oxidise to produce?

A

They are not readily oxidised

89
Q

How can aldehydes and ketones be identified?

A

The presence of a carbon-oxygen double bond, C=O, which is known as the carbonyl group

90
Q

Which can be readily oxidised, aldehydes or ketones?

A

Aldehydes

91
Q

What are 3 common oxidising agents used to determine aldehydes from ketones?

A

Acidified potassium dichromate solution, Fehling’s solution or Tollens’ reagent

92
Q

What is the definition of an aldehyde, how are they formed and what do they produce when oxidised?

A

Carbon compound which contain the -CHO functional group. They are formed by oxidation of primary alcohols and the oxidise to produce carboxylic acids.

93
Q

What is an antioxidant?

A

Compounds that slow oxidation reactions.

94
Q

Give an example of an antioxidant

A

Vitamin C, vitamin E etc.

95
Q

What is a carbonyl group?

A

The functional group present in ketones, C=O. Also present in aldehydes as part of their functional group, -CHO, and in carboxylic acids as part of their functional group, -COOH.

96
Q

What is the definition of denaturing of proteins?

A

Altering the shape of a protein by an increase in temperature or a reduction in pH

97
Q

What is a consequence of denaturing of proteins?

A

Loss of enzyme activity

98
Q

What are ketones?

A

Carbon compounds that contain the carbonyl group (C=O).

99
Q

How are ketones formed?

A

From the oxidation of secondary alcohols

100
Q

Ketones can be oxidised using mild oxidising agents such as acidified potassium dichromate solution. True or false?

A

False

101
Q

What are essential oils?

A

Oils extracted from plants.

102
Q

What are characteristics of essential oils?

A

They usually have distinctive smells, are non-polar, and often contain compounds known as terpenes.

103
Q

What is the definition of free radical?

A

Highly reactive atoms or molecules with unpaired electrons

104
Q

What is the definition of free radical scavenger?

A

A compound added to plastics, cosmetics and foods to prevent free radical reactions. They react with free radicals to produce stable molecules which terminates the reaction.

105
Q

What is the definition of a terpene?

A

Unsaturated compounds found in many plant oils.

106
Q

How are terpenes formed?

A

They are formed from the joining of isoprene units.

107
Q

What are the three steps of a free radical reaction?

A

Initiation, propagation and termination

108
Q

What happens in the initiation step of a free radical reaction?

A

U.V. light provides the energy for the homolytic fission of halogen into reactive halogen atoms or free radicals (atoms with an unpaired electron).

109
Q

What happens in the propagation step of a free radical reaction?

A

In this stage, free radicals collide with other species but the number of free radicals is maintained (hence the term propagation).These reactions continue until reactants are used up, or until free radicals are used up by collision with each other.

110
Q

What happens in the termination step of a free radical reaction?

A

In this stage, free radicals are used up by collision with each other.

111
Q

What does sun screen do?

A

Sun screens contain compounds that filter the UV light so that less UV reaches the skin

112
Q

What does sun block do?

A

Sun block contains compounds such as titanium dioxide that reflect the UV so that it does not reach the skin at all

113
Q

Many flavour and aroma molecules come from which family?

A

Aldehydes

114
Q

What happens to proteins during cooking?

A

The intermolecular bonds are broken allowing theproteins to change shape (denature). Thesechanges alter the texture of foods.

115
Q

What is the meaning of denature?

A

A permanent chemical change to the physical shapeof a protein/enzyme. This can happen at hightemperatures.

116
Q

What are essential oils?

A

Essential oils are concentrated extracts of the volatile,non-water soluble (hydrophobic) aroma compounds fromplants. The oils have the aroma of the plant from whichthey are extracted.

117
Q

How are essential oils extracted from plants?

A

Steam distillation

118
Q

What can happen when skin is exposed to uv rays?

A

Exposure to UV light can result in molecules gaining sufficient energy for bonds to be broken. This is the process responsible for sunburn and also contributes to aging of the skin

119
Q

What is the meaning of unsaturated?

A

Compounds which have double (or triple) covalent bonds between carbon atoms e.g. alkenes such as ethane.

120
Q

What is substitution?

A

A reaction where one atom is replaced by another atom.

121
Q

What ways can volume be measured?

A

Either by using a conical flask on top of a balance to measure loss of gas, with a cotton plug used to prevent spray OR by using a gas syringe

122
Q

How can you increase surface area?

A

By breaking large lumps into smaller pieces

123
Q

What is enthalpy change?

A

The difference in potential energy between reactants and products

124
Q

What is the definition of an activated complex?

A

An intermediate structure formed in the conversion of reactants to products. The activated complex is the structure at the maximum energy point along the reaction path

125
Q

What are the two main types of bonding in an element?

A

Metallic bonding and covalent bonding

126
Q

What is the definition of electrostatic attraction and how is it determined?

A

The strength of the electrostatic forces between two atoms is determined by the size of each atom’s charge and the distance between the two atoms. A very positive atom right next to a very negatively charged atom will have a strong electrostatic attraction while they would have a much smaller attraction if spaced far apart. The atoms may be drawn to each other depending the the strength of other forces acting on the atoms

127
Q

What is a temporary dipole?

A

Formed in all atoms where an excess of electrons is formed at one part of the atom. Temporary dipoles are the basis for London dispersion forces

128
Q

What is a standard solution?

A

A solution of known concentration

Higher Chemistry 2016 (5 decks)

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