Download Kinetic Theory of Matter

Mr Daniel Worrall
Mr Worrall
Mr Dan
IGCSE Chemistry
UNIT 10: Structure and Bonding
UNIT 1: Periodic Table
UNIT 2: Air and Water
UNIT 3: Acid, Alkalis and Salts
UNIT 4: Organic Chemistry
UNIT 5: Chemical Analysis Techniques
UNIT 6: Amount of Substance
UNIT 7: Electrochemistry
UNIT 8: Periodic Table 2
UNIT 9: Organic Chemistry 2
Core curriculum
Grades C to G available
Extended curriculum
Grades A* to G available
Paper 1 (45 minutes)
Compulsory A multiple-choice paper consisting of forty items of four-choice type.
The questions will be based on the Core curriculum, and will be of a difficulty appropriate to
grades C to G.
This paper will be weighted at 30% of the final total available marks.
Either:
Paper 2 (1 hour 15 minutes)
Core theory paper consisting of 80 marks of
short-answer and structured questions.
The questions will be of a difficulty appropriate
to grades C to G.
The questions will be based on the Core
curriculum.
The Paper will be weighed at 50% of the final
total available marks.
Or:
Paper 3 (1 hour 15 minutes)
Extended theory paper consisting of 80 marks
of short-answer and structured questions.
The questions will be of a difficulty appropriate
to the higher grades.
A quarter of the marks available will be based
on Core material and the remainder on the
Supplement.
The Paper will be weighed at 50% of the final
total available marks.
Practical Assessment
Candidates will not be required to use knowledge outside the Core curriculum.
Paper 6 Alternative to Practical (1 hour). This is a written paper designed to test familiarity
with laboratory based procedures.
The practical assessment will be weighted at 20% of the final total available marks.
Bonding and Structure
Section 1:Kinetic particle theory
Learning objective
By the end of this period, candidates should
be able to :
Describe the states of matter and explain
their conversion in terms of the kinetic
particle theory;
What is matter?
Matter is defined as anything that
occupies space & has mass.
Examples ?
States of Matter
Matter can exist as a solid, liquid, gas.
Task: Fill in the blanks with ‘definite’ or ‘not definite’.
Physical state
Volume
Shape
Example
Solid
Ice
Liquid
Water
Gas
Water vapor
States of Matter
Matter can exist as a solid, liquid, gas.
Physical
state
Solid
Volume
Shape
Example
Definite
Definite
Ice
Liquid
Definite
Not definite
Water
Gas
Not definite
Not definite
Water vapuor
Solid, Liquid, Gas
Kinetic Theory of Matter
1. All matter is made of many small
discrete particles (atoms, ions, &
molecules)
 In solids, the particles are closely packed
in orderly manner.
 In liquids, the particles are not as closely
packed as solids and are arranged in
disorderly manner.
 In gases, the particles are distributed very
far apart in random manner.
Kinetic Theory of Matter
2. The particles are always in constant
random motion.
 In solids, the particles vibrate about their fixed
positions.
 In liquids, the particles move about sliding and
rolling past one other in random motion.
 In gases, the particles move about freely at
high speeds and in random motion.
Interconversion between the three
states of matter
Task: Use the words below to fill in the gaps…











Evaporation
slowly
liquid
cooled
vibrate x 2
melting
quicker
expand
boiling
forces
gas
In-class activity
Crossword 10min
Plenary
List 3 things you learnt today
Homework
Homework sheet
Properties
Solid
Liquid
Gas
Shape
Fixed
Takes the
shape of the
container
Takes the
shape of the
container
Diagram showing the
arrangement of
particles
Forces of attraction
Very strong Strong
between particles
(Intermolecular forces)
Very weak
Motion of particles
Vibrate
about their
fixed positions
Roll and
slide past
each other
Random
motion
Move about
freely at high
speeds
Random
motion
Energy content
Low
Moderate
High
Physical properties of the solid, liquid
and gaseous states
Solid
Liquid
Gas
Volume
Fixed
fixed
Same as the
volume of the
container
Density
High
Moderate
Low
Compressibility
Cannot be
compressed
Cannot be
compressed
Highly
compressible
Fluidity
Does not
flow
Generally
flows easily
Flows easily
Heating curve
Bonding and structure
Part 2: Diffusion
Starter
Work with the person sitting next to you to
match the definitions to the correct word.
Solids, Liquids and Gases
1. Why can solids not flow?
Solid particles are not free to move about.
2.
Why can you squash gases more than liquids?
There are more spaces in between the particles in gases
than in liquids.
3. Which state of matter has a fixed shape and volume?
The solid state.
4. In which state are the particles closest together?
Solids.
5. In which state are the particles furthest apart?
Gases.
Can you write three bullet points about
each state of matter.
 Arrangement
The particles in a solid are arranged……….
 Forces
They have _________ interactive forces between
particles.
 Movement
Solid particles are unable to move about but can
___________
Learning objective
By the end of this period, candidates should
be able to :
Describe and explain diffusion;
Describe evidence for the movement of
particles in gases and liquids
Describe dependence of rate of diffusion
on molecular mass.
Diffusion is the random movement of
particles from a place of high
concentration to a place of low
concentration.
How Does Diffusion Work?
Initially the
aftershave
particles and air
particles are
separate
When allowed to,
the aftershave
particles begin to
move through the
available spaces…
Eventually the
aftershave
particles and gas
particles in the air
are totally mixed.
In LIQUIDS diffusion occurs a lot MORE SLOWLY because there
are NOT AS MANY GAPS in between the particles.
Diffusion
Diffusion is the seemingly random
movement of a substance from where
these particles are in high concentration to
where there are fewer.
The diffusion stops
where there is no
concentration
gradient existing.
The diffusion of gases
The lighter the particles of gas, the
faster the gas will diffuse.
Example: A particle of ammonia gas has
about half the mass of a particle of
hydrogen chloride so it will diffuse faster.
This is shown in your notes. The cloud
formed when the two gases meet is nearer
to the hydrogen chloride than the
ammonia.
Bonding and structure
Part 3: Atom
Starter
What is diffusion?
Learning objective
By the end of this period, candidates should be
able to :
State the relative charges and approximate
relative masses of protons, neutrons and
electrons;
Define proton number and nucleon number;
Calculate the proton number and mass
number from given information.
Element
Elements are substances that cannot be
chemically broken down into simpler
substances.
It is made of one type of atom…
History of the Atom
Democritus:
Ancient Greek Philosopher-Scientist,
‘a tomos’ – cannot be cut.
The problem: he was unable to provide the
evidence needed to convince people that atoms
really existed.
Atom: The smallest part of an
element that can exist as a stable
entity.
History of the Atom
 In 1808, an English school teacher
named John Dalton proposed that
atoms could not be divided and
that all atoms of a given element
were exactly alike.
Dalton’s theory is considered the foundation for
the modern atomic theory.
Dalton’s theory was developed with scientific
basis and was accepted by others.
History of the Atom
At the end of the nineteenth century, a scientist called
J.J. Thomson discovered the electron.
Thomson suggested that they could only have come
from inside atoms. So Dalton's idea of the indestructible
atom had to be revised.
Thomson imagined the electrons as the bits of plum in a
plum pudding
History of the Atom
In 1872-1937, Rutherford et al. ran
experiments
to
determine
the
structure of an atom.
He found a dense, positively charged central region
containing most of the atomic mass and that the atom is
mostly space.
History of the Atom
 In the 1920’s deBroglie & Shrodinger
showed that the “solar system”
model of the atom was incorrect.
Instead, electrons orbit the nucleus
in orbitals.
 This is called quantum mechanics. We
will look at this in our next lesson.
Even Smaller Particles!
• For some time people thought atoms were
the smallest particles and that they could
not be broken into anything smaller.
• We now know that atoms are themselves
made from even smaller and simpler
particles.
• These particles are
• Protons
• Neutrons
• Electrons
Structure of Atoms
Neutron
The protons and neutrons are found in the
middle of the atom, this is called the nucleus.
Proton
Electron
The electrons orbit around the
outside of the nucleus.
Lithium atom
Properties of Sub-atomic Particles
There are two properties of sub-atomic
particles that are especially important:
Mass
Electrical charge
Particle
Charge
Relative Mass
Location in atom
Protons
+1
1
In nucleus
Neutrons
0
1
In nucleus
Electrons
-1
negligible
Outside nucleus
Element atoms contain equal numbers of protons and
electrons and so have no overall charge
An example
 There are 12
electrons
• There are 12
protons
• There are 24 protons
and neutrons in the
nucleus
• There are 12
neutrons
Potassium
19 electrons
19 protons
39 protons and
neutrons in the
nucleus
20 neutrons
Working out the numbers of protons and neutrons
No of protons = ATOMIC NUMBER of the atom
The atomic number is also given the more descriptive name of proton number.
No of protons + no of neutrons = MASS NUMBER of the atom
The mass number is also called the nucleon number.
This information can be given simply in the form:
How many protons and neutrons has this atom got? The atomic number counts
the number of protons (9); the mass number counts protons + neutrons (19). If
there are 9 protons, there must be 10 neutrons for the total to add up to 19.
Atomic number (Z)=number of protons in
the nucleus,
Mass number (A)=number of protons
+number of neutrons.
A
Z
X
Bonding and structure
Part 4:Isotopes
Atom: The smallest part of an
element that can exist as a stable
entity.
Structure of Atoms
Neutron
The protons and neutrons are found in the
middle of the atom, this is called the nucleus.
Proton
Electron
The electrons orbit around the
outside of the nucleus.
Lithium atom
Learning objective
By the end of this period, candidates should be
able to :
Define isotopes;
State the two types of isotopes as being
radioactive and non-radioactive;
State one medical and one industrial use of
radioactive isotopes;
Describe radioactive isotopes, such as 235U
as a source of energy.
Starter
Atom
24
13
X
28
13
X
Number of
protons
Number of
neutrons
Number of
electrons
Isotopes
Isotopes are atoms of the same element
with different mass numbers;
They have the same number of protons
and electrons in each atom, but different
numbers of neutrons in the nucleus.
Properties of Isotopes
Same chemical propertiesthe same
number of electrons;
Different physical properties the different
masses of the atoms
Relative atomic masses Ar
The relative atomic mass (Ar ) is the
average mass of an atom of an element,
taking account of its natural isotopes and
their percentage abundance.
Radio-isotopes
Some isotopes have unstable nuclei; they
are radio-isotopes and emit various forms
of radiation.
Uses of isotopes:
Carbon Dating
Carbon has three isotopes: C-12 and C13 are stable. C-14 is unstable and emits
alpha particles
Used to find the age of ancient
materials.
Living wood has a tiny proportion of
radioative carbon C-14
The Shroud of Turin
Oxford University, the
University of Arizona, and
the Swiss Federal Institute
of Technology, agreed with
a dating in the 13th to 14th
centuries (1260–1390).
Smoke Detectors
 It can detect
particles of smoke
that are too small to
be visible.
 It includes a tiny
mass of radioactive
americium-241, which
is a source of alpha
radiation.
 The radiation passes
through a chamber.
 Any smoke that
enters the chamber
absorbs the alpha
particles, setting off
the alarm.
Medical Tracers
 PET scan
 The PET scanner detects
gamma rays
Thickness Control in
Manufacturing
235
U (Homework)
Write about some of the advantages and
disadvantages of using 235 U as a source
of energy, possible issues for discussion
include the long term nature of nuclear
energy (sustainable long after coal and oil
run out) and environmental considerations
such as the disposal of radioactive waste
(make it simple but clear, 150-200 words.)
Structure and Bonding
Part 5: Elements, mixtures and
compounds
What is…
An atom?
An element?
A compound?
A mixture?
What is…
 An atom?
The smallest part of an element.
 An element?
Something made up of only one type of atom or
something that cannot be broken down by chemical
means.
 A compound?
Two or more elements chemical joined.
 A mixture?
Two or more elements or compounds which are NOT
chemically joined.
Drawing
Use
and
An atom
An element
A compound
A mixture
to represent
Drawing
An atom
An element
A compound
A mixture
or
What are these?
 Element, compound or mixture?
 Which might be Neon, air, oxygen, water, carbon
dioxide?
How many atoms are present in the
molecules below?
Oxygen O2
Iron oxide Fe2O3
Sodium chloride NaCl
Copper sulphate CuSO4
Ammonia NH3
Copper oxide CuO
Methane CH4
Water H2O
Odd one out
Magnesium, aluminium, lead, silicon
Ca, Cu, Cl, Cs
CO, Co, Ca, Cu
Helium, argon, hydrogen, krypton
Li, Na, K, Fe
Lithium, nitrogen, oxygen, carbon
Unit 10: Structure and
Bonding
Part 6: Metallic Bonding
Describe the properties of metals and non
metals
Describe how metals are used according
to their properties
Describe the structure of metals and how
the structures result in a metals properties
Describe the structure of alloys
The Periodic Table
Non Metals
H
He
1
2
Li
Be
B
C
N
O
F
Ne
3
4
5
6
7
8
9
10
Na
M
g
Al
4
11
13
P
S
Cl
Ar
15
16
17
18
12
K
Ca
Sc
Ti
V
Cr
19
20
21
22
23
24
M
n
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
26
27
28
29
30
31
32
33
34
35
36
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
43
44
45
46
47
48
49
50
51
52
53
54
25
Rb
Sr
Y
Zr
Nb
37
38
39
40
41
M
o
42
Cs
Ba
La
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
55
56
57
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
Metals
Al
Au
Ti
Fe
Cu
Properties of Materials
Ductile
Can be drawn into wires.
Strong
Resistant to forces.
Brittle
Easy to break (but hard).
Malleable
Transparent
Electrical conductor
Electrical insulator
Heat conductor
Heat insulator
Flexible
Sonorous
Can be hammered into shape.
‘See-through’.
Lets electricity flow through it easily.
Does not let electricity flow through it easily.
Lets heat through it easily.
Does not let heat through it easily.
Can change its shape without snapping.
Make a ringing sound when struck.
Properties of Materials
Property
Metals
Appearance
Shiny
Melting and boiling
point
Density
Strength
Malleability
Ductility
Heat Conductivity
Electrical
Conductivity
Non-Metals
What is the structure of metals?
The atoms in a pure metal are in
tightly-packed layers, which form
a regular lattice structure.
sea of electrons
The outer electrons of the metal
atoms separate from the atoms
and create a ‘sea of electrons’.
These electrons are delocalized
and so are free to move through
the whole structure.
The metal atoms become positively
charged ions and are attracted to
the sea of electrons. This attraction
is called metallic bonding.
metal ions
Why are metals strong?
Metals are usually strong, not brittle. When a metal is hit,
the layers of metal ions are able to slide over each other,
and so the structure does not shatter.
metal before it is hit
metal after it is hit
force
force
The metallic bonds do not break because the delocalized
electrons are free to move throughout the structure.
This also explains why metals are malleable (easy to shape)
and ductile (can be drawn into wires).
How do metals conduct heat and electricity?
Delocalized electrons in metallic bonding allow metals to
conduct heat and electricity.
For example, when a metal is
heated, the delocalized electrons
gain kinetic energy.
These electrons then move faster
and so transfer the gained energy
throughout the metal.
This makes heat transfer in
metals very efficient.
Delocalized electrons also
conduct electricity through
metals in a similar way.
heat
Metals
positive ions
A metal structure is an ordered
pattern of positive ions in a ‘sea’
of negative electrons.
free electrons
Electrical Conductors
Metals are able to conduct electricity because…… (Complete this sentence)
Ductility
Electrons act as a type of (lubricant/bond) between the layers of (atoms/ions). This
explains why it’s possible to pull metals to form wires.
Melting Point
The strength of metallic bonds depends on the number of outer
neutrons/protons/electrons in the atoms (the more outer neutrons/protons/electrons the
stronger the bonds.
Metals
The key to understanding a metal’s
properties lies in its structure
positive ions
A metal structure is an ordered
pattern of positive ions in a ‘sea’ of
negative electrons.
GCSE Additional Science
Chapter 7
free electrons
Ductility
Electrical
Conductors
Connecting the
sides to a battery
makes the electrons
move from the
negative side
towards the positive
– this is the flow of
current.
Explaining the
properties of
METALS
Electrons act as a type of
lubricant between the
layers of ions. This
explains why it’s possible
to pull metals to form wires.
Melting Point
The strength of metallic bonds depends on the
number of outer electrons in the atoms (the more
outer electrons there are , the higher the melting
point).
Alloys
The atoms in pure iron are arranged in
densely-packed layers. These layers
can slide over each other. This makes
pure iron a very soft material.
The atoms of other elements are
different sizes. When other elements are
added to iron, their atoms distort the
regular structure of the iron atoms.
It is more difficult for the layers of iron
atoms in steel to slide over each other and
so this alloy is stronger than pure iron.
Unit 10: Structure and
Bonding
Part 7: Ionic Bonding
Lesson Objectives
Describe the build-up of electrons in ‘shells’ and understand the significance
of the noble gas electronic structures and of valency electrons.
Describe the formation of ions by electrons loss or gain.
Describe the formation of ionic bonds between elements from Groups I and
VII.
Describe the formation of ionic bonds between metallic and non-metallic
elements.
Describe the lattice structure of ionic compounds as a regular arrangement
of alternating positive and negative ions.
BONDING
Ionic Structures
GCSE Additional Science
Chapter 7
Sodium chloride is formed when atoms of sodium bond with atoms of chlorine.
Cl-
Na+
+) [2.8.1]
Sodium
Sodiumatom
ion (Na
(Na)
[2.8]
-) [2.8.8]
Chlorine
Chlorideatom
ion (Cl
(Cl)
[2.8.7]
Both atoms are trying to achieve a full set of outer electrons. They can do this if the
sodium atom gives its outer electron to the chlorine atom.
We now have a sodium ion Na+, and a chloride ion Cl-.
BONDING
Ionic Structures
GCSE Additional Science
Chapter 7
Na+
Cl-
Sodium ion (Na+) [2.8.]
Sodium chloride (salt)
Chloride ion (Cl-) [2.8.8]
BONDING
So there are two types of ion:1)
Ionic Structures
Positive ion (cation) – the atom has lost an electron
or electrons.
2)
Negative ion (anion) – the atom has gained
electron(s).
GCSE Additional Science
Chapter 7
The ions attract and the attraction is ionic bonding.
The oppositely charged ions attract each other. They cluster around each other
(six Cl- around each Na+ and vice versa) to make an ionic giant structure.
Six Chloride
ions cluster
around one
Sodium ion
Molecular structure of Sodium Chloride
(Click molecule to show animation)
Six Sodium
ions cluster
around one
Chloride ion
PROPERTY
DUE TO
High melting point
Strong electrostatic forces of attraction
between the ions. A lot of energy is
needed to break them.
Solid ionic compounds do not
conduct electricity.
The ions are held in fixed positions, and
are not free to move.
Molten ionic compounds
conduct electricity.
Melting has separated the ions so that
they can move past each other.
Unit 10: Structure and
Bonding
Part 8: Covalent Bonding
BONDING
Covalent Bonding
GCSE Additional Science
Chapter 7
Non-metal atoms bond with each other by sharing outer shell electrons.
This is called COVALENT BONDING.
Covalent bonding can produce:
•Small molecules of elements, e.g. H2
•Small molecules of compounds, e.g. HCl
•Giant molecules of elements, e.g. diamond and graphite
•Giant molecules of compounds, e.g. SiO2
BONDING
Covalent molecules
GCSE Additional Science
Chapter 7
Some elements form covalent compounds. This happens as atoms share electrons.
H
Cl
Chlorine atom (Cl) [2.8.7]
Hydrogen atom (H) [1]
Molecule of hydrogen chloride (HCl)
Hydrogen has the electron pattern of helium, and chlorine has the electron pattern
of argon.
This is written as H-Cl, where the ‘-’ represents a covalent bond (pair of
shared electrons).
Properties of molecular covalent compounds
GCSE Additional Science
Chapter 7
Melting points
Low
(attraction between molecules is weak)
Physical state at room
temperature
Gases or liquids with low boiling points or
solids with low melting points
(weak forces of attraction between molecules)
Electrical conductivity
Do not conduct electricity
(the molecules have no charge)
Solubility in water
Most are insoluble in water
An exercise to recognise atomic or covalent bonds.
(Only the outer shell is shown in the diagrams)
GCSE Additional Science
Chapter 7
H
Ca2+ 2Fionic
H
O
covalent
H
H
covalent
Cl
Mg2+ Cl2ionic
Cl
covalent
O
H
Cu
N
H
H
covalent
Show the answers
Cu2+
O2ionic
Unit 10: Structure and
Bonding
Part 9: Giant Covalent
Bonding
Giant Covalent Structures
Comparing the properties of graphite and diamond
GCSE Additional Science
Chapter 7
Some covalent molecules exist as giant covalent structures. These have a high
melting point because all the atoms are held by strong covalent bonds. Graphite
and diamond are examples of giant covalent structures made up of a collection
of carbon atoms only.
PROPERTY
Appearance
Hardness
Conductivity
Melting point
Diamond
Graphite
Transparent crystals
Grey/ black shiny solid
Incredibly hard – used for cutting
glass and in drill bits for drilling
through rocks in the oil industry.
Very soft – used as a lubricant.
Also used to make pencils.
Electrical insulator
A non-metal that conducts
electricity. Used for making
electrodes.
Very high – over 3500°C.
Very high – over 3600°C.
An explanation of the properties of diamond and graphite
GCSE Additional Science
Chapter 7
Diamond
Every atom is bonded to 4 other
atoms. Every outer electron has
its role to play in the covalent
bonding that happens here. The
result is a very rigid structure. As
there are no free electrons, it
doesn’t conduct electricity and it’s
a good conductor of heat.
Graphite
Graphite has layers formed from
hexagonal rings – these layers can slide
over each other, and this is why it is used
as a lubricant.
Every carbon atom bonds strongly to other
carbon atoms by three covalent bonds.
The fourth outer electron in each atom is
free to move, and this is what makes
graphite a good conductor.
The future, and other forms of carbon
GCSE Additional Science
Chapter 7
Whilst experimenting with Fullerene C60, it
was found that other structures of carbon
could be formed. One of them is seen
below:
Fullerene C60
The carbon atoms are bonded
covalently into a football shape.
Carbon Nanotube
The nanotube is like rolled graphite.
1) It conducts electricity
2) It’s very small – 10,000 times thinner
than a human hair
Nanotube
3) Crystals can be grown inside it
Human
hair
4) They may solve the problem of how
to produce smaller circuits, where
they might replace wires.