Leaving Cert Chemistry Term Flashcards

1
Q

Dalton’s Atomic Theory

A
  1. All matter is made up of very small particles called atoms.
  2. All atoms are indivisible. They cannot be broken down into simpler particles.
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2
Q

Cathode rays

A

Streams of negatively charged particles called electrons. They travel in a straight lines from the cathode to the anode, are deflected by electric and magnetic fields, and have sufficient energy to move a small object such as a paddle wheel.

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3
Q

Element

A

A substance that cannot be split into simpler substances by chemical means

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4
Q

Dobereiner’s Triad

A

A group of 3 elements with similar chemical properties in which the atomic weight (relative atomic mass) of the middle element is approximately equal to the average of the other two.

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5
Q

Newlands Octaves

A

Arrangement of elements in which the first and eighth element, confusing from a particular element have similar properties

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6
Q

Mendeleev’s Periodic Law

A

When elements are arranged in order of increasing atomic weight (relative atomic mass), the properties of the element recur periodically

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7
Q

Atomic number

A

The number of protons in the nucleus of that atom

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8
Q

Modern Periodic TABLE

A

An arrangement of elements in order of increasing atomic number

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9
Q

Modern Periodic LAW

A

When elements are arranged in order of increasing atomic number, the properties of the elements recur periodically, .ie the properties displayed by an element are repeated at regular intervals in other elements

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10
Q

Mass number

A

The sum of the number of protons and neutrons in the nucleus of an atom of that element

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11
Q

Isotopes

A

Atoms of the same element which have different mass numbers due to the different number of neutrons in the nucleus

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12
Q

Relative atomic mass

A

The average of the mass numbers of the isotopes of the elements as they occur naturally.
Taking their abundances into account.
Expressed on a scale in which the atoms of the carbon 12 isotope have a mass of exactly 12 units

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13
Q

Compound

A

A substance that is made up of two or more different elements combined together chemically

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14
Q

Octet Rule

A

When bonding occurs atoms tend to reach an electron arrangement with eight electrons in the outermost energy level

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15
Q

Ion

A

A charged atom or group of atoms

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16
Q

Ionic bond

A

The force of attraction between oppositely charged ions in a compound. Ionic bonds are always formed by the complete transfer of electrons from one atom to another.

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17
Q

Molecule

A

A group of atoms joined together the smallest particle of an element or compound that can exist independently

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18
Q

Valency

A

The number of bonds the atom of an element forms when it reacts

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19
Q

Electronegativity

A

The relative attraction that an atom in a molecule has for the shared pair of electrons in a covalent bond

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20
Q

Polar covalent bond

A

A bond in which there is unequal sharing of the pair of electrons. This causes one end of the bond to be slightly positive and the other end slightly negative

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21
Q

Intramolecular forces

A

Bonding takes place within a molecule, i.e it holds the atoms together. Covalent bonding and polar covalent bonding are examples of intramolecular bonding

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22
Q

Intermolecular forces

A

The forces of attraction that exist between molecules. Van der Waals forces, dipole-dipole forces and hydrogen bonding are examples of intermolecular forces

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23
Q

Van der Waals forces

A

Weak attractive forces between molecules resulting from the formation of temporary dipoles. They are the only forces of attraction between non-polar molecules

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24
Q

Mole

A

Th amount of that substance that contains 6 x 10*23 particles of that substance

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25
Q

Dipole-dipole forces

A

Forces of attraction between the negative pole of one polar molecule and the positive pole of another polar molecule

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26
Q

Hydrogen bonds

A

Type of dipole-dipole attractions between molecules in which hydrogen atoms are bonded to nitrogen, oxygen or fluorine. The hydrogen atom carries a partial positive charge and is attracted to thr electronegative atom in another molecule. Thus, the hydrogen bond acts as a bridge between two electronegative atoms in separate molecules

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27
Q

Law of Conservation Mass

A

The total mass of the products of a chemical reaction is the same as the total mass of the reactants

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28
Q

Law of Conservation of Matter

A

In any chemical reaction, matter is neither created nor destroyed but merely changed from one form into another

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29
Q

Relative molecular mass

A

The average mass of one molecule of that compound compared with one twelfth of the mass of one atom of the carbon-12 isotope.

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30
Q

Gas

A

A substance that has no well-defined boundaries but diffuses rapidly to fill any container in which its placed

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31
Q

Boyle’s Law

A

At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure
pV= K

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32
Q

Charles’ Law

A

At constant pressure, the volume of a fixed mass of gas, is directly proportional to its temperature measured on the Kelvin Scale
V/T = k

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33
Q

Gay-Lussac’s Law of Combining Volumes

A

In a reaction between gases, the volumes of the reacting gases and the volumes of any gaseous products are in the ratio of small whole numbers provided the volumes are measured at the same temperature and pressure.

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34
Q

Avogadro’s Law

A

Equal volumes of gases contain equal numbers of molecules under the same conditions of temperature and pressure

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35
Q

Ideal gas

A

A gas that perfectly obeys all the assumptions of the kinetic theory of gases under all conditions of temperature and pressure.

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36
Q

Real gas

A

Differ from ideal gases because.

i) Forces pf attraction and repulsion do exist between the molecules and
ii) the volume of the molecule is not negligible

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37
Q

Arrehnius’ definition of an acid

A

A substance that dissociates in water to produce H+ ions

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38
Q

Arrhenius’ definition of a strong acid

A

A substance that almost completely dissociates in water to produce hydrogen (H+) ion

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39
Q

Arrhenius’ definition of a weak acid

A

A substance that only slightly dissociates in water to give hydrogen ions

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40
Q

Arrhenius’ definition of a base

A

A substance that dissociates in water to produce hydroxide ions

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41
Q

Arrhenius’ definition of a strong base

A

A substance that almost completely dissociates in water to give hydroxide ions

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42
Q

Arrhenius’ definition of a weak base

A

A substance that only slightly dissociates in water to produce hydroxide ions

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43
Q

Brønsted-Lowry’s definition of a strong acid

A

A good proton donor

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44
Q

Brønsted-Lowry’s definition of a weak acid

A

A poor proton donor

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45
Q

Brønste Lowry’s definition of a strong base

A

A good proton acceptor

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46
Q

Brønsted-Lowry’s definition of a weak base

A

A poor proton acceptor

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47
Q

Conjugate acid base pair

A

Any pair consisting of an acid and a base that differ by one proton

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48
Q

Salt

A

The substance formed when the hydrogen ion from an acid is replaced by a metal or an ammonium ion

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49
Q

Neutralization

A

The reaction between an acid and a base to form a salt and water

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50
Q

Solution

A

A completely perfect mixture of a solute and a solvent. In a solution the particles of the solute are uniformly distributed throughout the solvent

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51
Q

Molarity

A

The number of moles of solute per litre of solution

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52
Q

Standard solution

A

A solution whose concentration is accurately known

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53
Q

Primary standard

A

A substance that can be obtained in a stable, pure and soluble solid form so that it can be weighed out and dissolved in water to give a solution of accurately known concentration

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54
Q

Titration

A

A laboratory procedure where a measured volume of one solution is added to a known volume of another solution until the reaction is complete

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55
Q

Energy level

A

The fixed energy value that an electron in an atom may have

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56
Q

Ground state

A

The electrons occupy the lowest available energy levels

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57
Q

Excited state

A

The electrons occupy a higher energy levels than those available in the ground state

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58
Q

Heisenbergs Uncertainty Principle

A

It’s impossible to measure at the same time both the velocity and the position of an electron

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59
Q

Sublevel

A

A subdivision of a main energy level and consists of one or more orbitals of the same energy

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60
Q

Principles of mass spectrometry

A

Charged particles moving in a magnetic field are deflected to different extents according to their masses and are thus separated according to these masses

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61
Q

Electron configuration

A

Shows the arrangement of electrons in an atom of an element

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62
Q

Aufbau Principle

A

When building up the electron configuration of an atom in its ground state the electrons occupy the lowest available energy levels

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63
Q

Hund’s Rule of Maximum Multiplicity

A

When two or more orbitals of equal energy are available the electrons occupy them singly before filling them in pairs

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64
Q

Pauli Exclusion Principle

A

No more than two electrons may occupy an orbital and they must have opposite spin

65
Q

Transition metal

A

One that forms at least one ion with a partially filled d sublevel

66
Q

Sigma bond

A

Formed by the head on over lap of two orbitals

67
Q

Pi bonds

A

Formed by the sideways overlap of porbitals

68
Q

Atomic radius

A

Half the distance between the nuclei of two atoms of the same element that are joined together by a single covalent bond

69
Q

First ionisation energy

A

The minimum energy required to remove the most loosely bound electron from a neutral gaseous atom in its ground state

70
Q

Second Ionisation energy

A

The energy required to remove an electron from an ion with one positive charge in the gaseous state

71
Q

Radioactivity

A

The spontaneous breaking up of unstable nuclei with the emission of one or more types of radiation

72
Q

Nuclear reaction

A

A process that alters the composition, structure or energy of an atomic nucleus

73
Q

Half life

A

The time taken for half of the nuclei in any given sample to decay

74
Q

Radioisotope

A

Radioactive isotope

75
Q

Radiocarbon dating

A

A technique used to determine the age of an object containing carbon. It is based on the ratio of carbon-14 to carbon-12 in the object

76
Q

Molecular formula

A

A formula that shows the number and type of each atom present in a molecule of that compound

77
Q

Empircal formula

A

The formula showing the simplest whole number ratio of the numbers of different atoms present in the molecule

78
Q

Oxidation

A

When an element loses electrons
Or
Oxidation number is increased

79
Q

Reduction

A

When an element gains electrons
Or
Oxidation number decreases

80
Q

Oxidising agent

A

A substance that brings about oxidation in other substances

81
Q

Reducing agent

A

A substance that brings about reduction in other substances

82
Q

Oxidation number

A

The charge that an atom has or appears to have when electrons are distributed according to certain rules

83
Q

Rate of reaction

A

The change in concentration per unit time of any one reactant or product

84
Q

Instantaneous rate of reaction

A

The rate of reaction at any one particular time during the reaction

85
Q

Catalyst

A

A substance that alters the rate of a chemical reaction but is not consumed in the reaction

86
Q

Enzyme

A

A substance that is produced by a living cell and acts as a biological catalyst

87
Q

Homogeneous catalyst

A

Catalysis in which both the reactants and the catalyst are in the same phase

88
Q

Heterogeneous catalysis

A

Catalysis in which the reactants and the catalyst are in different phases

89
Q

Autocatalysis

A

A catalysis in which one of the products of the reaction acts as a catalyst for the reaction

90
Q

Catalytic converter

A

A device in rhe exhaust system of a motor vehicle which contains catalysts to convert pollutants in the exhaust gases to less harmful substances

91
Q

Catalyst poison

A

A substance that makes a catalyst inactive

92
Q

Effective collision

A

One that results in the formation of products

93
Q

Activation Energy

A

The minimum energy that colliding particles must have for a reaction to occur

94
Q

Reaction Profile Diagram

A

A graph that shows the change in energy of a chemical reaction with time as the reaction progresses

95
Q

Reversible reaction

A

The products react to give back the reactants

96
Q

Chemical equilibrium

A

A state of dynamic balance in a reversible reaction where the rate of the forward reaction is the same as the rate of the backward reaction

97
Q

Dynamic State

A

The reactants are continuously forming products and the products are continuously forming reactants

98
Q

Dynamic equilibrium

A

The rate of the forward reaction is equal to the rate of the backward reaction

99
Q

Le Châteliers Principle

A

If a stress is applied to a system at equilibrium the system re-adjusts to relieve the stress applied

100
Q

Acid base indicator

A

As substance that changes colour according to the pH of the solution in which it is placed

101
Q

Range of an indicator

A

The pH interval over which there is a clear change of colour for that indicator

102
Q

Hard water

A

Water that will not easily form a lather with soap. Hardness in water is caused by Ca(2+) or Mg(2+) ions dissolved in the water

103
Q

Temporary hardness

A

Hardness that can be removed by boiling the water

104
Q

Permanent hardness

A

Hardness which cannot be removed by boiling the water

105
Q

Complexometric titration

A

A titration involving the formation of a complex between metal ions and a reagent such as edta. In this type of titrations the end point is marked by a sharp decrease in the concentration of free metal ions

106
Q

Flocculation

A

The coming together of small suspended particles in the water

107
Q

Flocculating agents

A

A chemical added to water to coagulate suspended particles and thus help sedimentation to take place

108
Q

Biochemical oxygen demand

A

The amount of dissolved oxygen consumed by biological action when a sample of water is kept at 20*C in the dark for five days

109
Q

Eutrophication

A

The enrichment of water with nurtrients leading to excessive growth of algae and other plants

110
Q

Primary treatment of sewage

A

Mechanical process in which large solids are removed by screening and some suspended solids are removed by settlement

111
Q

Secondary treatment of sewage

A

Biological oxidation process in which the levels of suspended and dissolved organic materials are reduced

112
Q

Tertiary treatment of sewage

A

A process involving the removal of phosphorus compounds by precipitation and the removal of nitrogen compounds by biological and ion exchange methods

113
Q

Principle of colorimetry

A

The amount of absorbance of light by a coloured solution is proportional to the concentrarion of the solution

114
Q

Electrolysis

A

The use of electricity to bring about a chemical reaction in an electrolyte

115
Q

Electrolyte

A

A compound which when molten or dissolved in water will conduct an electric current

116
Q

Electroplating

A

A process where electrolysis is used to put a layer of one metal on the surface of another

117
Q

Electrochemical series

A

A list of elements in order of their standard electrode potentials

118
Q

Organic chemistry

A

The study of compounds containing carbon

119
Q

Hydrocarbon

A

A compound that contains carbon and hydrogen ONLY

120
Q

Fossil fuels

A

Fuels that were formed from the remains of plants and animals that lived millions of years ago

121
Q

Saturated compound

A

A compound which there are only single bonds between the carbon atoms in the molecule

122
Q

Homologous series

A

A series of compounds of similar chemical properties
Showing gradations in physical properties
Having a general formula for its members
Each member having a similar method of preparation
Each member differing from the previous member by a CH2 unit

123
Q

Structural isomer

A

Compounds with the same molecular formula but different structural formulas

124
Q

Unsaturated compounds

A

One that contains one or more double or triple bonds between the atoms in the molecule

125
Q

Aliphatic compound

A

An organic compound that consists of open chains of carbon atoms and closed chain compounds that resemble them in chemical properties

126
Q

Aromatic compounds

A

Compounds that contain a benzene ring structure in their molecule

127
Q

Octane number

A

A measure of the tendency of the fuel to resist knocking

128
Q

Catalytic cracking

A

The breaking down of long-chain hydrocarbon molecules by the action of heat and catalysts into short-chain molecules for which there is greater demand

129
Q

Heat of reaction

A

The heat change when the number of moles of reactants indicated in the balanced equation for the reaction react completely

130
Q

Heat of combustion

A

A substance is the heat change when one mole of the substance is a completely burned in excess oxygen

131
Q

Kilogram calorific value

A

The heat energy produced when 1 kg of the fuel is completely burned in oxygen

132
Q

Bond energy

A

The average energy required to break one mole of a particular covalent bond and to separate the neutral atoms completely from each other

133
Q

Heat of neutralisation

A

The heat change when one mole of H+ ions from an acid reacts with one mole of OH- ions from a base

134
Q

Heat of formation

A

The heat change that takes place when one mole of a compound in its standard state is formed from its elements in their standard states

135
Q

Hess Law

A

If a chemical reaction takes place in a number of stages the sum of the heat changes in the separate stages is equal to the heat change if the reaction is carried out in one stage

136
Q

Chloroalkane

A

A compound in which one or more of the hydrogen atoms in an alkane molecule have been replaced by chlorine atoms

137
Q

Functional group

A

An atom of group of atoms which is responsible for the characteristic properties of an organic compound or a series of organic compounds

138
Q

Primary alcohol

A

One where the carbon atom joined to the -OH group is attached to only one other carbon atom

139
Q

Secondary alcohol

A

Where the carbon atom joined to the -OH group is attached to two other carbon atoms

140
Q

Tertiary alcohol

A

Where the carbon atoms joined to the -OH group is attached to three other carbon atoms

141
Q

Condensation reaction

A

A chemical reaction in which two molecules combine to form a largee molecule with the loss of a smaller molecule such as water

142
Q

Steam distillation

A

A separation process used to isolate compounds at temperature below their decomposition temperatures. It is carried out by bubbling steam through the material and distilling off the immiscible liquids

143
Q

Principle of steam distillation

A

A mixtuee of two immiscible liquids boils at temperature that is below that of the boiling point of each of the individual liquids. The hot mixture of water vapour and oil is passed through a condensor and the distillate that is collected contains a mixture of water and oil

144
Q

Emulsion

A

A dispersion of small droplets of one liquid in another liquid in which it is not soluble

145
Q

Liquid liquid extraction

A

A technique in which two immiscible liquids are separated using a solvent in which one of the components of the mixture has a higher solubility than the other

146
Q

Substitution reaction

A

A chemical reaction in which the atom or group of atoms in a molecule is replaced by another atom or group of atoms

147
Q

Mechanism

A

The detailed step by step description of how the overall reaction occurs

148
Q

Chain reaction

A

A reaction that continues on and on because a product from step one of the reaction is a reactant for another step of the reaction

149
Q

Addition reaction

A

Two or more molecules react together to form a single molecule

150
Q

Polymers

A

Long chain molecukes made by joining together many small molecules

151
Q

Repeating unit

A

That part of the polymer whose repetition produces the complete polymer chain except for the end groups

152
Q

Elimination reaction

A

A small molecule is removed from a larger molecule to leave a double bond in the larger molecule

153
Q

Organic synthesis

A

The process of making organic compounds from simpler starting materials

154
Q

Recrystallisation

A

A process of repeated Crystallisation in order to purify a solid or to obtain more satisfactory crystals of a solid that is already pure

155
Q

Chromatography

A

A separation technique in which a mobile phase carrying a mixture moves in contact with a selectively adsorbent stationary phase

156
Q

Principle of gas chromatography

A

A gaseous mobile phase is in contact with a stationary phase and separation of the mixture occurs as a result of selective adsorbance of the components of the mixture on the stationary phase

157
Q

Principle of high performance

A

A liquid in mobile phase is in contact with a sationary phase and separation of the mixture occurs as a result of selective adsorbance of the components of the mixture on the starionary phase

158
Q

Principle of infra red spectrometry

A

Organic compounds absorb infra red radiation of certain frequencies. The combinations of frequencies that are adsorbed depend on the bonding within the molecule and are unique to the particular molecule

159
Q

Principle of ultraviolet absorption spectrometry

A

Absorbance is directly proportional to the concentration of a substance