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Chemistry > CHEMISTRY END OF YEAR EXAM > Flashcards

CHEMISTRY END OF YEAR EXAM Flashcards

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1
Q

Definition of relative molecular mass

A

The sum of the relative atomic mass

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2
Q

Definition of physical change

A

A type of change in which the form of matter is altered but one substance is not transferred into another (change can be reversed)

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3
Q

Definition of chemical change

A

Any change that results in the formation of new chemical substances involving breaking bonds between atoms.

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4
Q

Describe the effect of concentration on rate of reaction

A

The higher the concentration, the faster the rate of reaction because that means there will be more particles, particles will be closer together, and so there will be a greater chance of successful collisions and so the reaction rate is greater.

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5
Q

What is the minimum amount of energy needed for particles to react called ?

A

Activation energy

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6
Q

What is the activation energy ?

A

the minimum amount of energy needed for particles to react

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7
Q

Explain effect of particle size on rate of reaction

A

The smaller the particles, the more surface area and the more surface area, the fastest the rate of reaction because that means collisions are far more frequent and so more reactions happen in the same given time. Larger particles have less surface area with the same total volume.

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8
Q

Explain effect of catalysts on rate of reaction

A

A catalyst is a substance that speeds up the rate of a chemical reaction. A catalysts speed up the rate of reaction because it provides a surface for particles to stick to, lowering the activation energy required in a reaction, therefore more particles have enough energy to react.

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9
Q

What is a catalyst ?

A

A catalyst is a substance that speeds up the rate of a chemical reaction.

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10
Q

What are enzymes ?

A

Biological catalysts found inside the body. A catalyst is a substance that speeds up the rate of a chemical reaction.

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11
Q

Definition of relative atomic mass

A

The average mass of naturally occurring atoms of an element in a scale where the 12C atom has a mass of exactly 12 units.

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12
Q

What is diffusion ?

A

Particles in liquids and gases move randomly. When the particles collide, they bounce off each other and move away in different directions. This results in particles getting mixed up and spreading out in the space available.

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13
Q

Where can diffusion happen ? And where is it faster ?

A 
In lipids (gases and liquids)
But faster in gases because particles move faster
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14
Q

How does the relative molecular mass affects rate of diffusion ?

A

The higher the mass, the slower the rate of diffusion because the slower the particles move and collide and so the less kinetic energy they have. This means when colliding , large and heavy molecules will bounce off each other with less energy and so will diffuse more slowly ; they will spread out in the space available more slowly then light, fast moving particles.

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15
Q

What are relative charges of protons ?

A

+1

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16
Q

What are relative charges of neutrons ?

A

0 (neutral)

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17
Q

What are relative charges of electrons ?

A

-1

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18
Q

What is the relative mass of protons ?

A

1

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19
Q

What is the relative mass of neutrons ?

A

1

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20
Q

What is the relative mass of electrons ?

A

1/2000

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21
Q

What is the proton number ?

A

Down left number (atomic number)

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22
Q

What is the nucleon number ?

A

Upper number (mass number)

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23
Q

How are elements classified in the periodic table ?

A

Elements are arranged in order of increasing atomic number.

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24
Q

What do elements in the same group have in common ?

A

Elements in the same group have the same number of valence electrons (outer shell electrons) and the same chemical properties

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25
Q

What do elements in the same period have in common ?

A

They have the same number of shells

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26
Q

How does the metallic character vary down a group or across a period ?

A

Down a group = metallic character increases

Across a period = metallic character decreases

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27
Q

What is the valency of an electron ?

A

The number of electrons an atom has to share, lose or gain when forming a compound, to get a full outer shell.

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28
Q

What is the valency of sodium (11)

A

1

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29
Q

What are isotopes ?

A

Atoms of the same element which have the same proton number but a different nucleon number.

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30
Q

What are the 2 types of isotopes ?

A

Radioactive (radioisotopes) and non-radioactive isotopes

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31
Q

Why do isotopes have the same properties ?

A

Because they have the same number of electrons in their outer shell

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32
Q

State one medical use of radioisotopes

A

Used in cancer treatment

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33
Q

State one industrial use of radioisotopes

A

Used in smoke detectors

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34
Q

Why are radioactive isotopes different?

A

They give out radiation

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35
Q

Give an example of radioisotopes

A

Uranium - 235

36
Q

What is uranium - 235 ?

A

A radioisotopes that gives out radiation from its nuclei + it is a source of energy

37
Q

Describe the built up of energy in shells

A

Electrons are arranged in shells (or energy levels), filling the shell closest to the nucleus first. Elements in the same period have the same number of shells.

38
Q

State the two types of oxides

A

Basic or acidic oxides.

39
Q

Describe the relationship between metallic character and non-metallic character and oxides.

A

Most METAL oxides are BASIC oxides and most NON-METALLIC oxides are ACIDIC.

40
Q

How ar many basic oxides formed ?

A

By the direct combination of a METAL with OXYGEN. They act to form a salt + water.

41
Q

Describe how many acidic oxides are formed.

A

Many acidic oxides are formed by the direct reaction with OXYGEN.

42
Q

What is an element ?

A

An element cannot be split into any bring smaller by chemical means and contains only one kind of atom.

43
Q

What is a mixture ?

A

A mixture is made from 2 or more substances mixed in any proportions but not chemically bonded.

44
Q

What is a compound ?

A

A compound is made up of 2 or more elements joined together by chemical bonds.

45
Q

What are the properties of metals ?

A

1) high melting point
2) high density
3) lustrous (shiny when polished)
4) malleable (can be beaten in another shape with a hammer)
5) sonorous
6) conduct heat
7) conduct electricity
8) ductile (can be stretched into wires)
9) form basic oxides

46
Q

What are non-metals properties ?

A

1) low melting point
2) low density
3) dull surface (even when polished)
4) non-malleable (cannot be beaten in another shape with a hammer)
5) not sonorous
6) don’t conduct heat
7) don’t conduct electricity
8) brittle (hard and breaks easily)
9) form acidic oxides
10) dull

47
Q

How are ions formed ?

A

By electron loss or gain

48
Q

Describe the formation of ionic bonds between elements from groups I and VII

A

The charges of ions are related to the position of the element in the periodic table. For example,
group I elements need to lose 1 electron to become 1+ ion.
group VII elements need to gain 1 electron to become 1- ion.

49
Q

Describe the formation of ionic bonds between metallic and nonmetallic elements

A

Ionic bonds are formed when electrons are transferred from a metal to a non-metal. Because metals are at the left hand side of the periodic table, they tend to lose electrons and non-metals that are at the right hand side tend to gain electrons to become stable and get a full outer shell.
When a metal reacts with a non-metal, the metal atom gives electrons to the non-metal atom for both of them to become stable?

50
Q

Describe the lattice structure of ionic compounds

A

A regular arrangement of alternating positive and negative ions (cations and anions).

51
Q

Describe the formation of single covalent bonds

A

Some atoms like H2, O2, Cl2 need to share one pair of electrons to get a full outer shell. When one pair of electrons is shared, we call that a SINGLE BOND.

52
Q

What are the main 3 differences between ionic and covalent compounds ?

A 
Ionic compounds are soluble 
Conduct electricity
Have low volatility
Covalent compounds are insoluble 
Do not conduct electricity
Have high volatility
53
Q

Describe why are ionic compounds soluble in water

A

Because the water molecules are able to separate the ions from one another and keep the ions in solution.

54
Q

Explain why ionic compounds conduct electricity

A

ONLY WHEN MOLTEN
Because the ions in ionic compounds are free to move, otherwise, the ions would be packed together and would only vibrate in their fixed positions in the lattice.

55
Q

Why do covalent compounds not conduct electricity ?

A

Because they have no ions

56
Q

Explain why ionic compounds have low volatility

A

Because they have a high melting and boiling point because of the strong forces between the ions in the giant lattice.

57
Q

Explain why covalent compounds have high volatility

A

Because they have low melting and boiling points, because of the weak forces between the ions. (However there are some exceptions).

58
Q

Describe the giant covalent structure of diamond

A

Each carbon atom forms covalent bonds with 4 other atoms in a TETRAHEDRAL arrangement. Atoms are bonded together to form a giant lattice (= giant covalent structure).

59
Q

Describe the structure of graphite

A

Each carbon atom forms covalent bonds with 3 other atoms to form HEXAGONAL rings that exist in layers. The binding within the layer is strong but there are weak intermolecular forces between the layers.

60
Q

Relate graphite’s structure to its uses

A

Graphite is used as a CONDUCTOR because the bonds in it are very strong and therefore a lot of energy is required to break the bonds and as a LUBRICANT because the layers can slide over each other, because the forces between the layers are very weak.

61
Q

Relate diamond’s structure to its uses

A

Diamond is used for CUTTING TOOLS because

1) it has got a very high melting point because the covalent bonds in it are very strong and it requires a lot of energy to break the bonds
2) it is very hard because it has a tetrahedral shape which spreads the force throughout the whole structure

62
Q

Describe the macromolecular structure of silicon(IV) oxide

= silicon dioxide

A

It has a giant covalent structure composed of oxygen and silicon atoms. Each silicon atom is bonded to 4 oxygen atoms and each oxygen atom is bonded to 2 silicon atoms.

63
Q

Describe the similarities between diamond and silicon dioxide, reacting to their structure

A

1) they both have a HIGH MELTING POINT
Because the covalent bonds are very strong and so it requires a lot of energy to break the bonds.
2) they both DO NOT CONDUCT ELECTRICITY
because there are no ions or free electrons to carry charge.

64
Q

Formulae of sodium chloride

A

NaCl

65
Q

Formulae of calcium bromide

A

CaBr2

66
Q

Formulae of sodium hydroxide

A

NaOH

67
Q

Formulae of lithium carbonate

A

Li2CO3

68
Q

Formulae of ammonium nitrate

A

NH4NO3

69
Q

Formulae of magnesium hydroxide

A

MgOH2

70
Q

What are the 4 state symbols ?

A

(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous

71
Q

Why can explosions happen in flour mills, sawmills and coal mines ?

A

Because flour, wood dust and coal dust are very fine powders and so each particle has a very large surface area and so if these powders are ignited, they react rapidly with oxygen to cause explosion.
+ Particles are closer in mines and so they have a greater chance to collide and react, and the fact that smaller particles have a larger surface area increases the chance of frequent collisions.

72
Q

What is the rate if reaction ?

A

How quickly or slowly a reaction happens.

Rate of reaction = amount of product made/ time

73
Q

How can you measure how quickly reactants are used up or how quickly products are formed ?

A

Method 1 : following the change in the volume of gas given off using a GAS SYRINGE

Method 2 : following the change in the volume of gas given off by collecting the gas OVER WATER.

74
Q

What is the periodic table ?

A

A method of classifying elements, used to predict properties of elements

75
Q

What are group 1 metals called ?

A

ALKALI METALS

76
Q

What are alkali metals’ properties ?

A

1) low melting and boiling point (decreases down the group)
2) low density (increases down the group)
3) react with water (increases down the group)

77
Q

What are alkali metals ?

A

Group 1 metals, a collection of relatively soft metals

78
Q

What are group 7 elements called ?

A

HALOGENS

79
Q

What are halogens ?

A

Group 7, a collection of diatomic non metals (2 atoms in each molecule)

80
Q

What are halogens’ properties ?

A

1) colour trend gets darker as you go down the group
2) low density (higher as you go down the group)
3) make displacement reaction (less reactive as you go down the group)

81
Q

Describe the transition elements

A

Collection of metals having high densities, high melting points and forming coloured compounds and which, as elements and compounds, often act as catalysts

82
Q

Describe the noble gases

A

Unreactive, monoatomic gases because they do not need to gain, lose or share electrons to from compounds

83
Q

Uses of Noble gases

A

1) argon in lamps
Because it does not react with metal filament
2) helium for filling balloons
Because it is lighter than air, it has a low density, it does not burn

84
Q

How to test for CARBON DIOXIDE

A

LIMEWATER TEST :
Carbon dioxide will turn limewater milky.
Limewater is a solution of calcium hydroxide. When carbon dioxide is bubbled through it, a solid precipitate of calcium carbonate is formed. It is the calcium carbonate which will make the limewater milky?

85
Q

Test for HYDROGEN

A

POP TEST
A lighted wooden splint makes a popping sound in a test tube of hydrogen. Hydrogen reacts very quickly with oxygen to form water.

86
Q

OXYGEN test

A

RELIGHTING TEST

a glowing wooden splint relights in a test tube of oxygen.

Chemistry (13 decks)

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