1 I am confident that I understand this and I can apply this to problems ? I have some understanding but I need to revise this some more I don’t know this or I need help because I don’t understand it National 5 outcomes are in bold Underlying knowledge in non-bold Rates of Reaction Covered () How well can you do this? ? 1. The collision theory can be used to explain the effects of particle size and surface area on reaction rates ? 2. The collision theory can be used to explain the effects of concentration on reaction rates ? 3. The collision theory can be used to explain the effects of temperature on reaction rates ? 4. Average rate of reaction, or stage in a reaction, can be calculated from initial and final quantities and the time interval ? 5. Catalysts can be classified as either heterogeneous or homogeneous ?
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1
I am confident that I understand this and I can apply this to
problems
? I have some understanding but I need to revise this some more
I don’t know this or I need help because I don’t understand it
National 5 outcomes are in bold Underlying knowledge in non-bold
Rates of Reaction Covered
() How well can you
do this?
?
1. The collision theory can be used to explain the
effects of particle size and surface area on reaction
rates
?
2. The collision theory can be used to explain the
effects of concentration on reaction rates
?
3. The collision theory can be used to explain the
effects of temperature on reaction rates
?
4. Average rate of reaction, or stage in a reaction, can
be calculated from initial and final quantities and the
time interval
?
5. Catalysts can be classified as either heterogeneous
or homogeneous
?
2
Atomic structure:
Nuclide Notation, Ions and Isotopes
Covered
()
How well can you
do this?
6. Calculate the number of n, p and e from the mass
number and atomic number, and vice versa
?
7.State that an atom which has lost or gained electrons
is known as an ion.
?
8. Calculate the number of n, p and e from nuclide
notation, including ions, eg
37
C1-
17
?
9. State what is meant by isotopes ?
10. State that most elements exist as a mixture of
isotopes
?
11.State that the relative atomic mass of an element is
the average mass taking into account all the isotopes
present.
?
3
Chemical Formula and Equations
Covered
() How well can you
do this?
12.State that the chemical formula of a compound tells us
what elements are present and how many atoms of each.
?
13. Formulae can be written for 2 element compounds ?
14. Formulae can be written for names using prefixes,
including mono-, di-, tri-, tetra-.
?
15. Formulae can be written for compounds which include
Roman numerals in their names, eg iron (III) chloride.
?
16. Formulae can be written for compounds involving group
ions but not requiring brackets, eg Na2SO4.
?
17.Formulae requiring brackets can be written for
compounds, eg Mg(OH)2.
?
18.Chemical reactions can be described using word
equations
?
19. Chemical reactions can be described using chemical
symbol equations.
?
4
Covalent Molecular,Covalent network and Ionic Lattices
Covered
() How well can you
do this?
20. State that atoms can be held together by bonds ?
21. State that atoms can achieve a stable electron
arrangement
?
23. Describe the covalent bond in terms of atoms sharing
pairs of electrons
?
24. State that a molecule is a group of atoms held together
by covalent bonds
?
25. State that (usually) only atoms of non-metal elements
bond to form molecules
?
26.A diatomic molecule is made up of two atoms
There are 7 diatomic elements in the periodic table.
?
27.Explain the covalent bond as a situation in which two
positive nuclei are held together by their common
attraction for the shared pair of electrons
?
28.Atoms can share more than one pair of electrons ?
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leading to the presence of double and triple bonds.
29 Draw a diagram to show how the outer electrons
form a covalent bond
?
Covered
() How well can you
do this?
30.Draw diagrams to show the shape of simple two
element molecules
?
31.Covalent substances can exist as small molecules
known as covalent discrete molecules
?
32.Certain covalent substances can exist as a giant
network structure
?
33. A covalent network structure consists of a giant
lattice of covalently bonded atoms
?
34.Discrete covalent substances have low melting and
boiling points due to the weak forces of attraction that
need to be overcome
?
35. Covalent network substances have high melting and
boiling points due to the strong covalent bonds which
need to be broken.
?
36. Ionic bonding is the electrostatic force of ?
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attraction between oppositely charged ions
37. Ionic compounds are usually formed when metals
combine with non-metals
?
38. An ionic structure consists of a giant lattice of
oppositely charged ions
?
39.Ionic compounds have high melting and boiling points
as strong ionic bonds need to be broken to break down
the lattice
?
Covered
() How well can you
do this?
40. Ionic compounds do not conduct electricity in the
solid state since the ions are not free to move, but
these compounds do conduct electricity when dissolved in
water or when molten as the ions are now free to move
?
41. Different ionic compounds form different shaped
lattice structures.
?
Calculations involving Gram Formula mass, balanced equations and
concentration:
Balanced equations
Covered
() How well can you
do this?
42. Formulae equations can be balanced to show the ?
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relative number of moles of reactant(s) and product(s)
43. The gram formula mass of any substance is known
as the Mole
?
44. The number of moles can be calculated from the
mass of a substance and vice versa
?
45. The mass of a reactant or product can be
calculated using a balanced equation
?
Acids and Bases Covered
() How well can you
do this?
46. In water and neutral solutions, the concentration of
hydrogen ions (H+) is equal to the concentration of
hydroxide (OH-) ions
?
47. A very small proportion of water molecules will
dissociate into an equal number of hydrogen ions (H+)
and hydroxide ions (OH-)
?
48. An acidic solution contains more hydrogen ions (H+)
than hydroxide ions (OH-)
?
49. An alkaline solution contains more hydroxide ions
(OH-) than hydrogen ions (H+)
?
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50. The effect of dilution on the pH of an acid or alkali
is explained in terms of the decreasing concentration of
hydrogen and hydroxide ions.
?
51. A 10x dilution changes the pH number by 1 ?
52. pH is a measure of hydrogen ion (H+) concentration ?
53. Neutral solutions have an equal concentration of H+
and OH- ions
54. Neutralisation of an acid with either a metal
hydroxide(alkali) or a metal carbonate involves spectator
ions
?
Covered
() How well can you
do this?
55. A spectator ion is present during a chemical reaction
but does not take part in the reaction
?
56. Titration is an analytical technique used to
determine volumes involved in chemical reactions such as
neutralisation.
?
57. Indicators are often used to show the end-point of
a titration.
?
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Rate of Reactions
Before a reaction can occur the reactant molecules must collide and the collisions must have
sufficient energy to produce a product.
There are four factors that affect the rate of reactions
Particle size
Concentration
Temperature
Catalyst
Particle size
The smaller the particle size the faster the rate of reaction.
This is a result of smaller particles allowing a greater surface area of reacting molecules to
be in contact and therefore a greater chance of a successful collision.
Concentration
The higher the concentration, the faster the rate of reaction. This is because higher
concentrations have greater numbers of reacting molecules and therefore a greater chance
of successful collision.
Temperature
The higher the temperature, the faster the rate of reaction. When a substance is heated
the molecules are all given more energy. As a result they move faster; increasing the chance
of a successful collision.
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Catalyst
A catalyst speeds up the rate of reaction. A catalyst will remain unchanged during the reaction. The
mass of catalyst remaining at the end of a reaction is the SAME as the mass used at the start.
Catalysts which are in the same physical state as the reactants are known as HOMOGENEOUS
catalysts.
Catalysts which are in a different physical state as the reactants are known as HETEROGENEOUS
catalysts
Calculating the average rate of reaction
It is difficult to measure the rate at any one time as the rate is constantly changing.
However, it is possible to work out the average rate over a period of time.
average rate = change in quantity
change in time
In the example above the change in quantity is the change in volume of hydrogen. To
calculate the average rate for the first 20 seconds:
average rate = change in volume
change in time
= 40cm3
20s
= 2cm3s-1
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Atomic and Mass Number
Atoms of different elements are different and have a different number on the Periodic
Table called the atomic number.
The atomic number is the number of protons in an atom.
The sum of the protons and neutrons in an atom is known as the mass number.
Consider the information below about sodium in which the sodium atom is represented in
nuclide notation.
23
11
Sodium has an atomic number of 11, so it has 11 protons (positive charges).
The sodium atom has no overall charge so it must have 11 electrons (negative charges).
The number of neutrons is given by the mass number minus the atomic number
therefore sodium has 23-11=12 neutrons.
Isotopes and Relative Atomic Mass
Isotopes of an element are atoms with the same number of protons but a different number
of neutrons therefore isotopes have the same atomic number but a different mass
number.
Chlorine has two common isotopes
Cl Cl
ATOMIC No = 17 ATOMIC No = 17
MASS No = 35 MASS No = 37
17 protons 17 protons
17 electrons 17 electrons
18 neutrons (35-17) 20 neutrons (37 – 17)
The isotopes will react chemically the same way because they have identical numbers of
electrons. Most elements exist as a mixture of different isotopes.
The relative atomic mass of an element is the average atomic mass taking into account the
proportion of each isotope. The relative atomic mass of chlorine is 35.5.
Chorine has two isotopes 35Cl and 37Cl and the average mass is 35.5 is closer to 35 than 37.
This tells us that 35Cl is more abundant(large amount of) than 37Cl.
Na
35
17
37
17
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Ions
Ions are formed when atoms gain electrons to make negative ions or when atoms lose
electrons to form positive ions.
Cl- Na+
17 protons 11 protons
18 electrons (17+1) 10 electrons (11-1)
18 neutrons (35-17) 12 neutrons (23-11)
Bonding
Compounds are formed when atoms of different elements join together. These atoms are
held together by bonds. The atoms form bonds to achieve a full outer electron arrangement,
this is also known as a stable electron arrangement. This stable arrangement can be achieved
by two separate methods giving rise to two types of compounds, COVALENT and IONIC.
Covalent Molecules (Discrete Molecules)
Most covalent compounds exist as molecules, which are a group of usually non metal atoms,
held together by a covalent bond.
Covalent bonds are formed when electrons are shared between two positive nuclei. It is the
attraction between the negative pair of electrons and the positive nuclei that hold the atoms
together.
The seven diatomic elements exist as molecules with pairs of electrons shared between their
atoms.
The diagram above shows how the unpaired outer electron in a hydrogen atom links up with
another hydrogen atom to form a hydrogen molecule with a shared pair of electrons. Only
unpaired electrons can form bonds as shown in the formation of chlorine below.
35
17
23
11 Gained e- Lost e-
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Oxygen has two unpaired electrons in its outer electron arrangement and therefore can form
a double bond as shown.
The nitrogen atom has three unpaired electrons and can therefore form a triple bond
These diagrams can also be used to show how outer electrons form compounds. Again it is
only unpaired outer electrons that can form bonds some examples are shown below.
Hydrogen chloride
Nitrogen Hydride (Ammonia)
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Carbon tetrachloride
Carbon dioxide shows double bonds being formed in a compound.
Molecules also have distinctive shapes and fall into four main structures as shown below.
Linear structure include hydrogen chloride and carbon dioxide, H-Cl and O=C=O, both of
these structures are described as 2 D and flat.
V shaped include water and hydrogen sulphide, this is again a 2 D shape and flat.
Pyramidal is the shape that nitrogen hydride has and is described as 3 D. The solid wedge
bond is coming towards you and the dotted bond is going away from you.
The final shape is tetrahedral and again its described as 3D. Carbon hydride (methane) has
this shape.
Most covalent molecular compounds have low melting and boiling points, and are usually liquid
or gas at room temperature. When these compounds changes state it is not the strong
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covalent bonds inside the molecules that are broken but weak forces of attractions between
the molecules. This requires a lot less energy and hence the melting and boiling points are
low.
The bonds between these molecules are weak and easily broken.
Covalent Network
The second type of structure covalent compounds can have is network. This is a giant lattice
of millions of atoms joined together with strong covalent bonds. Unlike molecules these
structures have very high melting and boiling points. When these strutures change state a
lot of energy is required as its covalent bonds that are being broken and not weak forces of
attraction. Substances that have this network structure include diamond, graphit and silicon
dioxide. Some of the structures are shown below.
Tetrahedral structure of carbon atoms
Layers of carbon with delocalised electrons between them.