1. No category

KS4 Chemistry
The Periodic Table
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Contents
The Periodic Table
Elements and atomic number
Arranging elements
Patterns of behaviour
Patterns and electron structure
Summary activities
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What are all substances made of?
There are millions of different substances in the world, but
what are they all made of?
 Elements – the building blocks of all substances.
There are about 100 different elements in a variety of forms.
From sodium, a reactive metal…
…to gold, an unreactive metal.
From chlorine, a poisonous gas…
…to oxygen, a life-giving gas.
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Properties of elements
What is a property of an element?
A property is any characteristic of an element.
For example, here are some properties of sodium:
 metallic;
 highly reactive;
 solid but melts easily;
 feels light (low density).
It would be really useful to be able to predict properties
of elements instead of having to remember them!
Are there any patterns in the properties of elements?
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Properties and atomic number
The properties of an element depend on its atomic number.
What is the atomic number of an element?
atomic number = the number of protons in an atom
Atoms contain three types of particles:
Particle
Mass
Charge
proton
1
+1
neutron
1
0
electron
almost 0
-1
Where are these particles found in an atom?
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What is atomic number?
What are the particles in this helium atom?
proton
electron
neutron
What is the atomic number of helium?
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2
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Atomic number, charge and electrons
Atoms contain equal numbers of protons and electrons.
This means that atoms are neutral.
What is the charge of a fluorine atom?
9 protons
9 electrons
10 neutrons
= +9
= -9
= 0
Total charge =
0
What links atomic number and the number of electrons?
atomic number = the number of electrons in an atom
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Atomic structure revisited
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Contents
The Periodic Table
Elements and atomic number
Arranging elements
Patterns of behaviour
Patterns and electron structure
Summary activities
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Periodic table timeline
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Atomic number and patterns of behaviour
If the elements are arranged in order of increasing atomic
number, patterns in their properties can be seen.
reactive gases
reactive metals
H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K
unreactive gases
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Positions of similar elements
Compare the positions of similar elements:
reactive gases
reactive metals
H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K
unreactive gases
How many elements from one reactive gas to the next?
8
How many elements from one reactive metal to the next?
8
How many elements from one unreactive gas to the next? 8
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Mendeleev and the periodic table
Mendeleev created the first modern periodic table by
grouping together elements with similar properties.
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Arranging elements
Divide the elements at set intervals into separate rows:
cut here
cut here
cut here
H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K
Arrange these rows so elements with matching properties
are together:
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K
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Arranging elements into columns
When elements are arranged according to their properties
what patterns do you see?
hydrogen
is a special
case
H
He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K
reactive metals
reactive gases
unreactive gases
Similar elements go into the same columns.
Hydrogen is an exception – it is best positioned above the
reactive metals.
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The periodic table
Arranging all the elements by their atomic number and their
properties led to the creation of…
H
…the periodic table
He
Li Be
B C N O F Ne
Na Mg
Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg ? ? ? ? ? ? ?
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Missing elements!
In this periodic table the symbols are replaced by atomic
numbers. Some of the numbers are missing – where?
Two more rows of elements fit here.
1
3
4
11 12
2
They are called the lanthanides
5 6 7 8 9 10
and actinides and are only
shown on some periodic tables. 13 14 15 16 17 18
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
37 38 39 40 41 42 43 44 45 46 47 38 49 50 51 52 53 54
55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
87 88 89 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118
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The elements in the periodic table
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Columns of elements
What are columns of elements called?
1 2
H
groups
3 4 5 6 7 0
He
Li Be
B C N O F Ne
Na Mg
Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg ? ? ? ? ? ? ?
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Rows of elements
What are rows of elements called?
periods
1
H
2
Li Be
B C N O F Ne
3 Na Mg
Al Si P S Cl Ar
4
He
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
6 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
7 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg ? ? ? ? ? ? ?
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Contents
The Periodic Table
Elements and atomic number
Arranging elements
Patterns of behaviour
Patterns and electron structure
Summary activities
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Patterns: metals and non-metals
Where are these different types of elements grouped
together in the periodic table?
 metals
on the left and centre
 non-metals
on the right (except hydrogen)
 metalloids
between metals and non-metals
Metalloids aren’t a type of rock music fan!
Metalloids have some properties similar to metals and other
properties similar to non-metals.
Can you name a metalloid element?
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Metals, non-metals and metalloids
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Patterns: physical state
Where are these elements of different states grouped
together in the periodic table?
 solids
on the left, in the centre and on the right
 liquids
in the middle and on the right
 gases
on the far right (except hydrogen)
Only two elements are liquids at room temperature.
What are they?
 bromine and mercury
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Solids, liquids and gases
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Patterns: reactivity of metals
What happens to the reactivity of metals along a period?
What happens to the reactivity of metals down a group?
increase in reactivity
Which is the most reactive metal?
Li Be
Na Mg
Al
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg
increase in reactivity
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Which metal is more reactive?
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Patterns: reactivity of non-metals
Group 0 elements are the most unreactive of all elements.
For the remaining non-metals and metalloids, reactivity
increases up a group and along a period from left to right.
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increase in reactivity
Which is the
most reactive
non-metal/
metalloid?
increase in reactivity
He
B C N O F Ne
Si P S Cl Ar unreactive
Ge As Se Br Kr
Sb Te I Xe
At Rn
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Which non-metal is more reactive?
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Contents
The Periodic Table
Elements and atomic number
Arranging elements
Patterns of behaviour
Patterns and electron structure
Summary activities
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Patterns, atomic number and electrons
The periodic table shows that patterns in the properties of
elements are linked to atomic number.
H
Li Be
Na Mg
What links atomic number and
the properties of elements?
electrons
He
B C N O F Ne
Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg ? ? ? ? ? ? ?
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Atomic number and electrons
The properties of elements are hugely influenced by the
number and arrangement of electrons in the atom.
What links atomic number and the number of electrons in
an atom?
atomic number = number of protons
number of protons = number of electrons
atomic number = number of electrons
As atomic number increases by one, the number of electrons
also increases by one.
This means that the elements in the periodic table are also
arranged in order of the number of electrons.
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Electron shells
Electrons are arranged in shells around an atom’s nucleus.
Each shell has a maximum number of electrons that it can
hold. Electrons will fill the shells nearest the nucleus first.
1st shell holds
a maximum of
2 electrons
2nd shell holds
a maximum of
8 electrons
3rd shell holds
a maximum of
8 electrons
This electron arrangement is written as 2,8,8.
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Electrons in period 1
Elements in period 1 only have electrons in the first shell.
Why are there only two elements in period 1?
1
1
2
3
4
5
6
7
0
H
He
1
2
The first shell can only hold a maximum of two electrons,
so period 1 only includes the elements hydrogen and helium.
What is special about the outer shell of helium?
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Electrons in period 2
Elements in period 2 all have a complete first shell.
What happens to electrons in the second shell in period 2?
2
1
2
3
4
5
6
7
0
Li
Be
B
C
N
O
F
Ne
2,1
2,2
2,3
2,4
2,5
2,6
2,7
2,8
The second shell is completed one electron at a time going
across the period from left to right.
What is special about the outer shell of neon?
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Electrons in period 3
Elements in period 3 have complete first and second shells.
What happens to electrons in the third shell in period 3?
1
3
2
Na Mg
3
4
5
6
7
0
Al
Si
P
S
Cl
Ar
2,8,4
2,8,5
2,8,6
2,8,7
2,8,8
2,8,1 2,8,2 2,8,3
The third shell is completed one electron at a time going
across the period from left to right.
What is special about the outer shell of argon?
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Patterns of electron arrangements
Consider the electron arrangements of the first 20 elements
in the periodic table.
1
2
3
4
5
6
7
0
2
1
1
2
2,1
2,2
2,3
2,4
2,5
2,6
2,7
3
2,8,1
2,8,2
2,8,3
2,8,4
2,8,5
2,8,6
2,8,7 2,8,8
4
2,8,8,1 2,8,8,2
2,8
What is the pattern of outer shell electrons in a group?
What is the pattern of outer shell electrons across a period?
What is the pattern of full electron shells in a group?
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Electron trends in the periodic table
Trends down a group:
 the number of outer shell electrons is the same;
 the number of complete electron shells increases by one.
The number of a group is the same as the number of
electrons in the outer shell of elements in that group,
except for group 0.
Trends across a period:
 the number of outer shell electrons increases by one;
 the number of complete electron shells stays the same.
The point at which a new period starts is the point at which
electrons begin to fill a new shell.
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Electrons and groups
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Groups and periods
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What’s the electron arrangement?
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Names of groups in the periodic table
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Contents
The Periodic Table
Elements and atomic number
Arranging elements
Patterns of behaviour
Patterns and electron structure
Summary activities
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Glossary
 atomic number – The number of protons in an atom.






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Sometimes called the proton number.
electron arrangement – A shorthand way of writing the
number of electrons in an atom’s electron shells.
element – A substance made up of only one type of atom.
group – A column in the periodic table containing elements
with the same number of outer shell electrons and similar
chemical properties.
period – A row in the periodic table containing elements
with the same number of full electron shells.
periodic table – The table that lists all the elements in
order of increasing atomic number, arranged into groups and
periods.
property – Any characteristic of an element.
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Anagrams
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Matching elements and groups
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Multiple-choice quiz
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