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Nat 5 Chemistry > Unit 1- Chemical Changes and Structure > Flashcards

Unit 1- Chemical Changes and Structure Flashcards

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1
Q

What is the rate of a reaction?

A

The speed

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2
Q

What is the activation energy of a reaction?

A

The minimum amount of energy needed for a successful reaction.

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3
Q

What does the overall rate of a reaction depend on?

A

The frequency of the collisions between the particles

How much energy the particles collide with.

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4
Q

4 ways to increase the rate of a reaction:

A

Increase temperature

Increase concentration

Decrease particle size

Add a catalyst

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5
Q

What are catalysts?

A

Special chemicals that are added to increase the rate of a chemical reaction.

They take part in the reaction, but can be recovered unchanged and reused.

Biological catalysts are called enzymes.

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6
Q

Reaction rate graphs key points:

A

The steeper the line, the faster the reaction.

When the line becomes horizontal, the reaction has stopped.

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7
Q

Why is a reaction fastest at the beginning of the chemical reaction?

A

This is when the concentration of reactants is greatest.

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8
Q

Particles in an atom:

A

Protons, neutrons, electrons

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9
Q

Protons: position, relative mass and charge?

A

Position: nucleus

Relative mass: 1

Charge: +1

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10
Q

Neutrons: position, relative mass and charge?

A

Position: nucleus

Relative mass: 1

Charge: 0 (neutral)

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11
Q

Electrons: position, relative mass and charge?

A

Position: Orbiting nucleus

Relative mass: negligible

Charge: -1

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12
Q

Why are atoms electrically neutral?

A

Number of protons (+) = number of electrons (-)

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13
Q

What is the atomic number of an atom?

A

The number of protons in the nucleus of an atom.

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14
Q

What is the mass number of an atom?

A

The number of protons + the number of neutrons in the nucleus of an atom.

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15
Q

What is this called?

Mass number

               X <—— (symbol)

Atomic number

A

Nuclide notation

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16
Q

How are electrons arranged in an atom?

A

Electrons are arranged in shells or energy levels.

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17
Q

How many electrons do the first 3 shells/energy levels hold?

A

1st shell: 2

2nd shell: 8

3rd shell: 8

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18
Q

What is an isotope?

A

Atoms which have the same atomic number but a different mass number.

Isotopes have the name number of protons but a different number of neutrons.

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19
Q

What is the relative atomic mass of an isotope always closer to?

A

The most abundant isotope.

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20
Q

How do atoms achieve a stable electron arrangement?

A

By having a full outer electron energy shell.

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21
Q

What is an ion?

A

A charged particle.

Ions are formed when atoms lose or gain electrons to obtain the stable electron arrangement of a noble gas.

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22
Q

Positive ions have…?

A

Lost electrons

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23
Q

Negative ions have…?

A

Gained electrons

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24
Q

To achieve a stable electron arrangement, metals…?

A

Lose electrons forming positive ions.

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25
Q

To achieve a stable electron arrangement, non-metals…?

A

Gain electrons forming negative ions.

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26
Q

How do we know the charge of an ion?

A

The charge of an ion is the same as its valency.

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27
Q

What is an ion electron equation?

A

An equation that shows electrons being lost or gained.

Examples:

1) Na(s) ——> Na+ + e-

2) Cl + e- ——> Cl-

3) Mg ——> Mg2+ + 2e-

4) O + 2e- ——> O2-

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28
Q

What is an ionic bond?

A

The electrostatic attraction between positive and negative ions.

Bonds between metals and non-metals.

Ionic bonding involves the transfer of electrons.

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29
Q

What structures do ionic bonds form?

A

Ionic lattice.

Lattice structures of oppositely charged ions with each positive ion surrounded by negative ions and vice versa.

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30
Q

Ionic lattice melting and boiling points are…?

A

High

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31
Q

Ionic lattice state at room temperature?

A

Solid

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32
Q

Do ionic compounds conduct electricity?

A

Only when molten or in solution as the lattice structure breaks up allowing the ions to be free to move.

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33
Q

What is a covalent bond?

A

The attraction of two nuclei for a shared pair of electrons.

In covalent bonding, electrons are shared between non-metal atoms.

This allows the non-metal atoms to achieve a stable electron arrangement.

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34
Q

Types of covalent structures:

A

Covalent molecular

Covalent network

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35
Q

What is covalent molecular?

A

Small molecules containing a certain number of atoms held together by covalent bonds. (e.g. carbon dioxide)

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36
Q

What is covalent network?

A

A giant network of non-metal atoms held together by covalent bonds. (e.g. diamond)

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37
Q

Covalent molecular key points:

A

Strong covalent bonds within the molecules and only weak attractions between the molecules.

Low melting and boiling boiling points as only weak forces of attraction between the molecules are broken when a substance changes state.

Do not conduct electricity because they don’t have charged particles which are free to move.

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38
Q

Covalent network key points:

A

Have a giant network of strong covalent bonds within one giant structure.

Have very high melting and boiling points because the network of strong covalent bonds is not easily broken.

Do not dissolve.

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39
Q

Covalent network melting and boiling points are…?

A

Very high

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40
Q

Covalent network state at room temperature?

A

Solid

41
Q

Do covalent networks conduct electricity?

A

Never (except graphite)

42
Q

Covalent molecular melting and boiling points are…?

A

Low

43
Q

Covalent molecular state at room temperature?

A

Any state

44
Q

Do covalent molecular bonds conduct electricity?

A

Never (although water is a poor conductor)

45
Q

What is a diatomic molecule?

A

A molecule containing only two atoms.

46
Q

What are the 7 diatomic elements?

A

Iodine
Bromine
Chlorine
Fluorine
Oxygen
Nitrogen
Hydrogen

47
Q

What is a monatomic element?

A

One-atomed

All noble gases

48
Q

Shapes of simple covalent molecules:

A

Linear (one bond)

Angular (two bonds)

Trigonal Pyramidal (three bonds)

Tetrahedral (four bonds)

49
Q

What does it mean if a compound name ends in “ide”?

A

Made up of two types of elements.

50
Q

What does it mean if a compound name ends in “ite” or “ate”?

A

Made up of three types of elements, one which is oxygen.

51
Q

Definition of valency?

A

A term used to describe the combining power of an atom.

52
Q

What does “SVSDF” stand for?

A

Symbol
Valency
Swap
Divide (if possible)
Formula

53
Q

Roman numerals from 1-6?

A

1- I
2- II
3- III
4- IV
5- V
6- VI

54
Q

What is a group ion?

A

Group ions contain two or more atoms.

Most group ions have a negative charge.

55
Q

How can we determine the valency of a group ion?

A

Use the number of charges.

56
Q

What do we do when a formula contains more than one group ion?

A

The group ion must be written in brackets.

57
Q

Prefixes from 1-6?

A

1- Mono
2- Di
3- Tri
4- Tetra
5- Penta
6- Hexa

58
Q

Prefix rule:

A

If you see a prefix DO NOT use the SVSDF system.

59
Q

What does the ionic formulae include?

A

The charges present on each of the ions. (Charges are the same as the valency of the element.)

60
Q

Charge on an ionic compound?

A

Neutral

61
Q

The mole key points:

A

A mole is a unit of measurement.

For most elements, 1 mole is the relative atomic mass (RAM) in grams.

However, for the 7 diatomic elements, 1 mole is twice the RAM in grams.

The Gram Formula Mass (GFM) is the mass of 1 mole.

62
Q

Method on how to do calculations from balanced chemical equations:

A

1) Write a balanced chemical equation, unless already given.

2) Identify the two chemicals referred to in the question and write the mole ratio.

3) Gather information from the question.

4) Calculate the number of moles.

5) Use the mole ratio to calculate the number of moles of the substance you are trying to find.

6) Calculate the mass.

63
Q

How is a solution formed?

A

When a soluble substance is dissolved in a solvent.

64
Q

What does the concentration of a substance depend on?

A

How much of a substance is dissolved in it.

65
Q

What do we need to do to the volume if it’s in cm^3?

A

Divide by 1000 to make it into litres.

66
Q

Concentration, number of moles, volume, mass and GFM units:

A

Concentration: moles per litre (mol l^-1)

Number of moles: no units

Volume: litres (l)

Mass: grams (g)

GFM: grams (g)

67
Q

What numbers do acids show up as on the pH scale?

A

1-6

68
Q

What numbers do alkalis show up as on the pH scale?

A

8-14

69
Q

What number is a neutral solution on the pH scale?

A

7

70
Q

Hydrogen ion symbol?

A

H+

71
Q

Hydroxide ion symbol?

A

OH-

72
Q

What breaks down into hydrogen ions and hydroxide ions?

A

Water molecules

H2O <—> H+ (aq) + OH- (aq)

(Reversible reaction)

Only a few molecules are dissociated into free ions.

73
Q

An acidic solution has a greater concentration of…?

A

H+ ions

74
Q

An alkaline solution has a greater concentration of…?

A

OH- ions

75
Q

A neutral concentration has…?

A

An equal concentration of H+ and OH-

76
Q

Why is water a poor conductor of electricity?

A

It is mainly made of molecules and contains only a few ions.

77
Q

What happens when you dilute an acidic solution with water?

A

It will decrease the concentration of H+ ions and the pH will increase towards 7.

78
Q

What happens when you dilute an alkaline solution with water?

A

It will decrease the concentration of OH- ions and the pH will decrease towards 7.

79
Q

What forms an acidic solution?

A

Soluble non-metal oxides dissolving in water.

80
Q

What forms an alkaline solution?

A

Soluble metal oxides dissolving in water.

81
Q

What is the name of a substance that neutralises acids?

A

A base

82
Q

What is a base that dissolves in water called?

A

An alkali

83
Q

What happens in a neutralisation reaction?

A

An acid reacts with a base, causing the pH to move towards 7.

84
Q

Metal oxide + acid ——>

A

Salt + water

85
Q

Metal hydroxide + acid ——>

A

Salt + water

86
Q

Metal carbonate + acid ——>

A

Salt + water + carbon dioxide

87
Q

What type of salt does hydrochloric acid make?

A

Chloride

88
Q

What type of salt does sulfuric acid make?

A

Sulfate

89
Q

What type of salt does nitric acid make?

A

Nitrate

90
Q

How to name a salt?

A

1st part: first name of the base

2nd part: depends on the acid

Example:

Calcium carbonate + sulfuric acid ——> Calcium sulfate + water + carbon dioxide

91
Q

What is a precipitation reaction?

A

When two solutions are mixed together and one of the products is insoluble.

92
Q

How can we remove the insoluble solid (precipitate) from the liquid.

A

Filtration

93
Q

What does the precipitate take its name from?

A

The positive metal ion from one reactant and the negative ion from the other.

94
Q

What is the name of ions that are present in a reaction mixture but don’t take part?

A

Spectator ions

They appear unchanged on both sides of the chemical equation.

As a result, they are often left out (omitted) in the chemical equation.

95
Q

Why do we use an indicator in titrations?

A

To show the endpoint of the reaction.

96
Q

What piece of equipment should be used to accurately measure the volume of a liquid?

A

A burette/pipette

97
Q

What is the name of a solution of accurately known concentration?

A

Standard solution

98
Q

How to perform a titration with accuracy?

A

The conical flask should be sitting on a white tile. This will help you to observe colour changes more accurately.

All of the burette readings should be taken at eye level.

The titration should be repeated until two concordant results (within 0.2cm^3 of each other) are obtained.

99
Q

Titration calculations rule:

A

When using the results from a table for calculations, always ignore the rough titration result and calculate the average of the two concordant results.

Nat 5 Chemistry (3 decks)

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