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CFE Chemistry
Unit 1 Chemical Changes & Structure
Smithycroft Secondary School
National 4 Chemistry
Unit 1
Chemical Changes & Structure
Name
-1-
CFE Chemistry
Unit 1 Chemical Changes & Structure
Chemical Reactions
I can state the 4 signs of a chemical reaction
I can explain what is an element, compound and mixture
Chemistry is the study of chemical substances - what things are
made of, how they react with each other and how one substance can
be changed into another.
List the four signs of a chemical reaction
1.
2.
3.
4.
Lesson 2
Reaction rates
I can name four things which can speed up a chemical reaction
I can draw and interpret graphs to compare reaction rates
Chemical reactions can occur at different speeds or rates.
Consider the following chemical reactions and complete the
table.
Decide if they are slow, medium or fast and give
another example. Does your partner agree?
Reaction
Speed or rate
Iron nail rusting
Bomb Explosion
Making Toast
List the four ways of speeding up a chemical reaction
1.
2.
3.
4.
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Another Example
CFE Chemistry
Unit 1 Chemical Changes & Structure
Lesson 3
Inside the atom
I can name the 3 subatomic particles, explain where they are
found in an atom and state their charge
I can explain why atoms are electrically neutral
All elements are made up of small particles called ATOMS, with each
element made from its own unique type of atom. However, all atoms have
a similar atomic structure.
Pupil Activity: Investigating atomic structure
Complete the diagram by adding appropriate labels.
Even though atoms have these sub-atomic particles they are mostly
composed of empty space!!
Inside the atom
Imagine we enlarge an atom until it is the size of a football pitch. The
electrons would orbit through the goal posts, the nucleus would be the
size of a tennis ball on the centre spot and all the rest of the pitch would
be empty space!!!
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Complete the table below showing the location and appropriate charges
of subatomic particles.
Particle
Charge
Where is it found in atom
Electron
Neutron
Proton
Investigating atomic structure
Using the information in the table - complete the drawing in the
last column of the table. The first one has been done for you.
Element
Protons
Neutrons
Electrons
Helium
2
2
2
Atom Drawing
Electrons
Protons
neutrons
Lesson 3 continued
Inside the atom
Element
Protons
Neutrons
Electrons
Hydrogen
1
0
1
Carbon
6
6
6
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Atom Drawing
CFE Chemistry
Boron
Unit 1 Chemical Changes & Structure
5
6
5
Can you explain why atoms are electrically neutral from table above?
____________________________________________
Did you notice that the electrons are in layers? We will discuss this
further in electron arrangements.
Lesson 4
Atomic & Mass Number
I can explain what an atomic number and a mass number are in
an atom
I can state the mass of subatomic particles
Look at the periodic table on page 8 of chemistry data book. Notice that
each element has a number above it - this is its unique ATOMIC
NUMBER. The atomic number used to be called the proton number, as it
tells us the number of protons in the nucleus.
Atoms are electrically neutral because the number of protons (+ve
charge) is the same as the number of electrons (-ve charge).
Investigating atomic number
Using your knowledge of atoms complete the table below:
Atomic
Element
Symbol
Number
O
12
Lithium
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Protons
Electrons
CFE Chemistry
Unit 1 Chemical Changes & Structure
Be
14
Flourine
The mass of an atom is very small, at 0.000000000000000000000000167g.
This means that a single crystal of an element has millions of atoms!
Atoms are so small that they are not measured in grams they are
measured in atomic mass units (amu).
Atomic & Mass Number
Atomic Mass
Complete the table.
Particle
Charge
Approximate
Where is it
mass (a.m.u.)
found in atom
Electron
Neutron
Proton
Did you notice that an electron has a mass of almost zero?
This means that 99.9% of the mass of an atom is located in the nucleus.
The number of protons + neutrons in an atom is known as the MASS
NUMBER. Chemists use a special system for writing the mass number,
atomic number and symbol for an element. It is
Mass no.
Atomic No.
X
called nucleotide notation:
The mass number is given on top with the
atomic number written underneath. The atomic
number is always the smaller number!
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Atomic & Mass Number
Can you work out the number of protons, electrons and neutrons in an
atom?
Complete the table below using the information provided.
Nucleotide
Protons
Neutrons
Electrons
23 Na
11
12 C
6
16 O
8
35 Cl
17
4 He
2
1.
2.
What is meant by the atomic number?
What is meant by the mass number?
Atom story board
Choose one of the elements from the table above and complete a story
board about your element.
Remember to include:
 Number of protons, neutrons, electrons
 Location of subatomic particles
 Label nucleus
 Atomic number
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Lesson 5
Electron Arrangements
I can state and draw the electron arrangements for the first
20 elements
I can state that elements with the same outer electrons are
grouped together.
How are the electrons arranged in an atom?
Each element has a unique number of electrons orbiting the nucleus of its
atoms. This number is the same as its atomic number (number of protons
in the nucleus).
How are these electrons arranged around the nucleus?
1st energy level
2nd energy level
3rd energy level
There is a maximum of 2 electrons in the first shell, 8 in the second and
18 in the third shell.
The electrons are organised in these shells or layers and are known as
the electron arrangement or electron configuration. The electron
arrangements for all atoms can be found in the data booklet.
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Electron Arrangements
Investigating electron arrangement
Using your data booklet, show the electron arrangement for
the first 10 elements. Draw these in your jotter.
Complete the following diagram to briefly describe how the electrons are
arranged in an atom.
__________ atom
_______________
first _____ level
11+
______ ______ level
third ______ level
Explain how the layers are numbered.
The number of electrons in the last or furthest away layer is called the
number of outer electrons.
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Electron Arrangements
How does the electron arrangement affect the chemical properties of
each element?
Consider the following questions:
1.
What is the electron arrangement of the sodium atom?
2.
What do you notice about all the group 1 electron arrangements?
3.
How is group 0 different from other groups with respect to outer
electrons?
4.
Can you describe a general rule that links the number of electrons
to the group number?
5.
Can you explain how the outer number of electrons or group number
affects the way in which an atom reacts and so affects its chemical
properties?
6.
Without looking at a periodic table, say which period and in which
group you would place the element with electron arrangement
2, 8, 18, 18, 3. Now check to see if you were correct.
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Lesson 6
Investigating bonding
I can state that compounds are held together by bonds
I can name the two different types of bonding when elements
join together, which affect the properties of their compounds
Atoms join together and form bonds between them to make molecules.
Investigating bonding
Aim:
To identify whether compounds which either contain 2
non-metals or metals and non-metals behave differently due
to their bonding
Substance
Contains metal /
Conducts electricity
Melting point
non metals?
Solid
High / low
Solution
Sodium Chloride
Gelatin
Wax
Glucose
Copper Chloride
Potassium Bromide
Name two differences between the properties of compounds containing
either 2 non-metals or a metal and a non-metal.
1.
2.
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Investigating bonding
How do non-metal atoms bond together?
Non-metal atoms like hydrogen and oxygen join to form water by bonds
called covalent bonds.
What is a covalent bond?
Negative
Electron
Positive
nucleus
e
e
+
H
+
H
Area of attraction
Both positive nuclei attracted to shared
pair of negatively charged electrons
A covalent bond is the attraction of two nuclei for a shared pair of
electrons. In covalent bonding electrons are shared between atoms.
As well as having it’s own name, each substance can also be
represented by a chemical formula. Here is water:
Key:
Water
Formula: H2O
Ammonia
Formula:
Methane
Formula:
Nitrogen
Oxygen
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Carbon
Hydrogen
CFE Chemistry
Unit 1 Chemical Changes & Structure
Investigating bonding
Ionic bonding Instead of sharing electrons, atoms can transfer
electrons. This is called ionic bonding, and occurs when metals bond with
non-metals.
Na (2,8,1)
Cl (2,8,7)
Na+ (2,8)
Cl-(2,8,8)
Remember atoms are trying to achieve full outer electron levels (e.g. like
Neon 2,8) when they bond, so they can get a stable electron arrangement
like a noble gas!
So that’s what they do they transfer an electron. Ionic bonding involves
the transfer of outer electrons.
 Sodium atom 2,8,1
electron level
Loses an electron to get to a full outer
electron arrangement now 2,8.
 Chlorine atom 2,8,7
electron level
Gains an electron to get to a full outer
electron arrangement now 2,8,8.
Complete the following:
There are two types of bonding between atoms
Bonding.
and
Ionic/covalent bonding involves the
sharing of electrons. Ionic/covalent bonding involves the
electrons.
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of
CFE Chemistry
Unit 1 Chemical Changes & Structure
Lesson 7
Covalent Bonding and Formulae
I can show covalent bonding as a sharing of electrons by
drawing non-metal atoms joined together in a molecule
I can work out the chemical formula given the number of atoms
of each element in a molecule
Can you build & write the chemical formula for the
following substances?.
Chemical
Complete the following table.
Diagram
butane
vinegar
acetone
Ethylene glycol
(antifreeze)
aspirin
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Chemical Formula
CFE Chemistry
Unit 1 Chemical Changes & Structure
Covalent Bonding and Formulae
Drawing Molecules
Use molecular models to build the molecules on the following
table. There cannot be any holes left in the atoms. Draw the
molecules into the table under 2-D structural formula. Afterward your
teacher will tell you the names of these shapes of molecules.
Compound
2-D
Chemical
Structural
formula
formula
Shape
Hydrogen
Chloride
Carbon
chloride
Hydrogen
oxide
Carbon
Hydride
What exactly do atoms do to form a bond?
Here are simplified electron arrangement diagrams of a hydrogen atom
and a chlorine atom. (Only the outer electrons are shown in fluorine).
H
1
F
2,7
Can you see a way that both of these atoms can have full, stable electron
arrangements? Draw it on your show me board and in your jotter.
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Covalent Bonding and Formulae
Non-metal atoms achieve a full, stable electron arrangement by
__________ electrons with each other. This __________ of electrons
is what makes a __________ bond.
More Examples:
Draw Electron sharing diagrams (with outer electrons only) for
the compounds of:
a)
Hydrogen and chlorine
b)
Hydrogen and oxygen
c)
Nitrogen and hydrogen
d)
Carbon and hydrogen
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Lesson 8
Ionic bonding
I can explain that an ionic bond is caused by electrostatic
attraction between ions (charged particles)
Ionic compounds are formed between metal and non-metal elements.
When we make an ionic compound we transfer electrons.
Na 2,8,1
Cl 2,8,7
Na+ (2,8)
Cl- (2,8,8)
These charged particles are called ions.
Ions: Atoms that have a charge because they have gained or lost
electrons.
Atoms form ions by __________ or __________ electrons.
Metal
atoms always __________electrons and so always form __________
charged ions.
Non-metal atoms form ions with __________ charges
because they always __________ electrons. An atom will gain or lose as
many __________ as it needs to get a __________ outer shell.
Once the ions are formed they are held together in a lattice by bonds
caused by electrostatic attraction between positive and negative ions.
Na+
Cl-
Ionic Bond: The electrostatic attraction between positive and
negative ions.
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Bonding Revision
1.
Draw a table and use it to classify these properties as
belonging to ionic or covalent substances
Low melting and boiling
points
Form ions when dissolved or
molten
Usually exists as liquids
or gases at room
temperature
Never conduct electricity
High melting and boiling
points
Conduct electricity when
molten or dissolved
2.
Usually exists as
solids
at room temperature
Work out if these compounds are ionic or covalent.
Name
Formula
Nitrogen
N2
Bonding
Name
Formula
Carbon
CO2
dioxide
Calcium
CaO
Oxide
Lithium
Li2S
sulphide
Iodine
I2
Methane
CH4
Aluminium
Al2O3
Sodium
Na2S
oxide
sulphide
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Bonding
CFE Chemistry
Unit 1 Chemical Changes & Structure
Lesson 9 Formula of Compounds
I can state the chemical formulae of two element compounds.
I can explain what the endings –ide, -ate and –ite mean
Extension: I can work out chemical formulae using valencies
(SVX)
Can you work out the formula and names of compounds?
Compounds are made when different elements join together, using either
covalent or ionic bonds.
These compounds get their names from the
elements that make them up. The ending of the compound gives us a clue
to the elements present.
Write the definitions for –ide, -ite and – ate, then complete
the following table:
-ide ending means
-ite or –ate ending means
Compound
Elements
Caesium Bromide
Potassium Chloride
Magnesium phosphate
Boron Fluoride
Aluminium oxide
Sulphur oxide
Potassium Sulphate
Calcium Sulphite
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Formula of Compounds
In the previous table we identified the elements present, but how do
we work out the actual formula?
For some elements, including the noble gases, the formula is
just the element symbol. They are said to be monatomic (one
–atomed). Complete the table:
He
Ne
Ar
Kr
Xe
Rn
Symbol
Element
He
Ne
Ar
Kr
Xe
Rn
There are 7 non-metal elements that exist as diatomic molecules (2
atoms joined together).
H H
Element
hydrogen
N
N
Nitrogen
Oxygen
O O
Flourine
Chlorine
F
F
Bromine
Iodine
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Chemical Formula
CFE Chemistry
Unit 1 Chemical Changes & Structure
Diatomic – 2 atoms joined together
In most compounds we have to use the combining power of an element or
valency to work out the chemical formula.
Valency – the combining power of an atom
Different elements have different valencies depending on their position
in the periodic table.
Group No
1
2
3
4
5
6
7
Valency
1
2
3
4
3
2
1
1
2
3
4
5
6
7
0
H
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
Ga
Ge
As
Se
Br
Kr
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Chemical Formulae -SVX
To work out the formula we use 3 stages. S- symbol, V- valency, Xcross over
e.g. NaCl
S - Symbols:
Na Cl
V - Valency
1
1 (Na group 1, so valency 1, Cl group 7 so valency 1)
X - X Cross over valencies Na Cl
• Formula
NaCl
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CFE Chemistry
Unit 1 Chemical Changes & Structure
If the valency is 1 you do not need to show this in the final formula
because the chemical symbol represents one atom.
Formula of Compounds
Use the valency method to write the formula for each of the
following.
Answer in your jotter.
(a)
hydrogen fluoride
(f)
hydrogen chloride
(b)
hydrogen sulphide
(g)
phosphorous hydride
(c)
nitrogen chloride
(h)
nitrogen fluoride
(d)
phosphorous chloride
(i)
silicon hydride
(e)
carbon oxide
(j)
silicon oxide
Meaningful names
There are some covalent compounds with names which have prefixes
which can be used to write the formula. The valency method should not
be used when writing the formula for these compounds.
Complete the table below.
Prefix
Meaning
Compound
mono
carbon monoxide
di
sulphur dioxide
tri
sulphur trioxide
tetra
carbon tetrachloride
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Formula
CFE Chemistry
Lesson 10
Unit 1 Chemical Changes & Structure
Chemical Equations
I can write a word equation for a chemical reaction
I can write simple symbol equations from word equations
Can you write a balanced chemical equation?
Word equations
A word equation is a statement showing the reactants on the left
separated by an arrow from the products on the right. For example, zinc
combines with oxygen to form zinc oxide. The word equation for this is:
zinc + oxygen
zinc oxide
Complete word equations for the following reactions:
(a)
Hydrogen joins up with oxygen to form water.
(b)
Carbon dioxide and water are produced when methane reacts with
oxygen.
(c)
Iron is formed when iron oxide is heated with carbon monoxide.
Carbon dioxide is also formed.
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CFE Chemistry
Unit 1 Chemical Changes & Structure
Chemical Equations
Words to symbols
Use symbols and formulae to write a chemical equation for
each of the following reactions.
(a) carbon monoxide + oxygen
carbon dioxide
(b) sulphur + oxygen
sulphur dioxide
(c) carbon + oxygen
carbon monoxide
Lesson 11
Conservation of Mass
I can show by experiment the conservation of mass
What happens to the mass of materials when chemical changes take
place?
When a firework sparkler is lit a chemical changes take place –light and
heat are given off in an
change. The magnesium atoms present
in the sparkler are reacting with the oxygen molecules in a combustion
reaction to form magnesium oxide.
Word equation:
Chemical equation:
- 24 -
CFE Chemistry
Unit 1 Chemical Changes & Structure
Learning Outcomes - Chemical Changes & Structure
Tick
Lesson
Learning Outcome
√
No.
1
2
2
3
I can state some signs of a chemical reaction
I can name 3 things which can speed up a chemical
reaction
I can draw and interpret graphs to compare
reaction rates
I can name the 3 subatomic particles, explain
where they are found in an atom and state their
charge
3
I can explain why atoms are electrically neutral
4
I can explain what an atomic number and a mass
number are in an atom
4
I can state the mass of subatomic particles
5
5
6
6
7
7
I can state and draw the electron arrangements
for the first 20 elements
I can state that elements with same number of
outer electrons are grouped together.
I can state that compounds are held together by
bonds
I can state that there are two different types of
bonding (ionic and covalent) when elements join
together, which affect the properties of their
compounds
I can show covalent bonding as a sharing of
electrons by drawing non-metal atoms joined in a
molecule
I can work out the chemical formula given the
number of atoms of each element in a molecule
- 25 -
CFE Chemistry
Unit 1 Chemical Changes & Structure
Learning Outcomes - Chemical Changes & Structure
Tick
Lesson
Learning Outcome
√
No.
8
9
9
9
I can explain that an ionic bond is caused by
electrostatic attraction between ions (charged
particles)
I can state the chemical formulae of two element
compounds
I can explain what the endings –ide, -ite and –ate
mean
Extension: I can work out chemical formulae using
valencies (SVX)
10
I can write a word equation for a chemical reaction
10
I can write simple symbol equations from word
equations
11
I can show by experiment the conservation of mass
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