EdExcel Additional Science

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EdExcel Additional Science
In Your Element
W Richards The Weald School
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The structure of the atom
The Ancient Greeks used to believe that
everything was made up of very small particles.
I did some experiments in 1808 that proved this
and called these particles ATOMS
Dalton
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Mass and atomic number
Particle Relative Mass Relative Charge
Proton 1 1
Neutron 1 0
Electron Very small -1
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Mass and atomic number
How many protons, neutrons and electrons?
1
11
16
H
B
O
1
5
8
23
35
238
Na
Cl
U
11
17
92
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Isotopes
An isotope is an atom with a different number of
neutrons
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Relative Atomic Mass
The relative atomic mass of an element is the
average mass of a sample of those atoms.
For example, naturally-occuring chlorine consists
of 3 parts 35Cl for every 1 part 37Cl, so the
atomic mass of chlorine is
(3 x 35 1 x 37) / 4 35.5
Q. What is the relative atomic mass of magnesium,
which consists of 8 parts 24Mg, 1 part 25Mg and 1
part 26Mg?
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Electron structure
Consider an atom of Potassium
Potassium has 19 electrons. These electrons
occupy specific energy levels shells
The inner shell has __ electrons The next shell
has __ electrons The next shell has __
electrons The next shell has the remaining __
electron
Electron structure 2,8,8,1
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Trends in Group 1
Consider a sodium atom
Sodium ion
Now consider a potassium atom
Potassium ion
Potassium loses its electron more easily because
its further away potassium is MORE REACTIVE
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Trends in Group 7
Consider a flourine atom
Flouride ion
Now consider a chlorine atom
Chloride ion
Chlorine doesnt gain an electron as easily as
flourine so it is LESS REACTIVE
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Periodic Table Introduction
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Periodic table







Horizontal rows are called PERIODS
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The Periodic Table
Fact 1 Elements in the same group have the same
number of electrons in the outer shell (this
corresponds to their group number)
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Fe Ni Cu Zn Br Kr
Ag I Xe
Pt Au Hg

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The Periodic Table
Fact 2 As you move down through the periods an
extra electron shell is added
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Fe Ni Cu Zn Br Kr
Ag I Xe
Pt Au Hg

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The Periodic Table
Fact 3 Most of the elements are metals
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Fe Ni Cu Zn Br Kr
Ag I Xe
Pt Au Hg

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The Periodic Table
Fact 4 (Most important) All of the elements in
the same group have similar PROPERTIES. This is
how I thought of the periodic table in the first
place. This is called PERIODICITY.
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Fe Ni Cu Zn Br Kr
Ag I Xe
Pt Au Hg

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Bonding
Hi. My names Johnny Chlorine. Im in Group 7,
so I have 7 electrons in my outer shell







Id quite like to have a full outer shell. To do
this I need to GAIN an electron. Who can help me?
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Bonding
Here comes my friend, Sophie Sodium
Hey Johnny. Im in Group 1 so I have one
electron in my outer shell. I dont like having
just one electron so Im quite happy to get rid
of it. Do you want it?
Okay
Now weve both got full outer shells and weve
both gained a charge. Weve formed an IONIC bond.
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Ions
An ion is formed when an atom gains or loses
electrons and becomes charged
If we take away the electron were left with
just a positive charge
This is called an ion (in this case, a positive
hydrogen ion)
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Ionic bonding
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Some examples of binary salts
Magnesium chloride

MgCl2
Calcium oxide
CaO
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Electrolysis
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Electrolysis
Electrolysis is used to separate a metal from its
compound.
When we electrolysed copper chloride the _____
chloride ions moved to the ______ electrode and
the ______ copper ions moved to the ______
electrode OPPOSITES ATTRACT!!!
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Electrolysis equations
We need to be able to write half equations to
show what happens during electrolysis (e.g. for
copper chloride)
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2
2
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Purifying Copper
Solution containing copper ions
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Electrolysis of Aluminium Oxide
Overall
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Properties of metals
Metals have very high melting points (which means
that they are usually _____) whereas non-metals
will melt at lower ___________ All metals conduct
heat and __________ very well, whereas non-metals
dont (usually) Metals are strong and ______ but
bendable. Non-metals are usually _____ or they
will snap. Metals will _____ when freshly cut or
scratched, whereas non-metals are usually
dull. Metals have higher _______ than non-metals
(i.e. they weigh more) Metals can be used to make
______ (a mixture of different metals)
Words - alloys, electricity, solids, weak,
densities, temperatures, tough, shine
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Alloys
Steel is an alloy i.e. a mixture of metals.
Here are other alloys