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KS3 Chemistry

8E Atoms and
Elements
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2004

Contents

8E Atoms and Elements
What are atoms and elements?
Symbols for elements
Elements in the periodic table
Making compounds
Chemical reactions
Summary activities
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2004

How many different substances are there?

How many
different substances
can you think of?

There are millions of different substances!
What are they all made of?
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All substances are made of atoms
All substances are made of very tiny particles called atoms
...


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hydrogen and
oxygen atoms

carbon and
hydrogen atoms

iron, aluminium,
silicon, oxygen
and boron atoms

carbon, nitrogen,
hydrogen, oxygen
and sulphur atoms
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2004

What is an element?
All substances are made of very tiny particles called atoms
...
These are the elements
...

The elements are the building blocks of all other substances
...


Copper is an
element made up of
copper atoms only
...


Helium is an
element made up of
helium atoms only
...

In some elements, the atoms are joined in groups of two or
more
...

Oxygen is an
element made up of
oxygen atoms only
...

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2004

Contents

8E Atoms and Elements
What are atoms and elements?
Symbols for elements
Elements in the periodic table
Making compounds
Chemical reactions
Summary activities
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2004

Introducing chemical symbols
A standard set of symbols is used to represent elements:
The symbol for many of the more common elements uses
just the first letter of the name
...


Li = lithium
Al = aluminium
He = helium
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O = oxygen
N = nitrogen
I = iodine
Some of the symbols are not
always as you might expect
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1
...

e
...


N (not n) for nitrogen

2
...

e
...


Co (not CO) for cobalt

No, Watson! It was
carbon monoxide
poisoning – not cobalt
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1
...
Relative: sulphur, oxygen, nitrogen

SON

3
...
Group of fish: sulphur, hydrogen, oxygen,
aluminium

SHOAl

5
...
Combining the symbols of the atoms
in a molecule gives you the formula of the molecule
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© Boardworks Ltd 2005
2004

Contents

8E Atoms and Elements
What are atoms and elements?
Symbols for elements
Elements in the periodic table
Making compounds
Chemical reactions
Summary activities
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2004

Arranging elements

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Metal or non-metal?
Is this element a metal

or a non-metal ?
Hard to
say!

H
Li Be
Na Mg
K Ca Sc
Rb Sr Y
Cs Ba La
Fr Ra Ac
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B C N O
Al Si P S
V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se
Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po
Db Sg Bh Hs Mt ? ? ?

iron
antimony
(Sb)
iodine
(I) (Fe)
copper
(Cu)
phosphorus
(P)
sulfur
(S)
magnesium
(Mg)
Ti
Zr
Hf
Rf

F
Cl
Br
I
At

He
Ne
Ar
Kr
Xe
Rn

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2004

Metals and non-metals in the periodic table
The periodic table is a list of all the known elements which
are arranged according to the similarities in their properties
...

left and in the centre
...
sometimes like non-metals
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© Boardworks Ltd 2005
2004

Contents

8E Atoms and Elements
What are atoms and elements?
Symbols for elements
Elements in the periodic table
Making compounds
Chemical reactions
Summary activities
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2004

Combining elements
How is possible to have so many different materials from
a limited number of elements?

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Combining elements
How do you get so many
different cheeses?
What is the key ingredient in
all cheeses?
Milk is combined with a
small number of ingredients
under different conditions to
make a huge number of
different cheeses
...

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2004

What is a compound?
A compound is the substance produced when two or more
elements combine in a chemical reaction
...


Which two elements combine
to make the compound
carbon dioxide?
A compound is always made up of two or more
different types of atom
...


elements
carbon

oxygen
combines
with

A black solid
which can be
used as a fuel
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A colourless gas
which is used
to put out fires
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compound
water
to make

A colourless gas
which is essential
for life
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2004

Element or compound?

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Element or compound?

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2004

Contents

8E Atoms and Elements
What are atoms and elements?
Symbols for elements
Elements in the periodic table
Making compounds
Chemical reactions
Summary activities
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© Boardworks Ltd 2005
2004

Chemical reaction to make water
In a chemical reaction new substances are formed
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+
hydrogen

oxygen

water

The substances which combine in a reaction are the reactants
...

The products have different properties to the reactants from
which they are formed
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Atoms joining in a chemical reaction
When the two elements, hydrogen and oxygen, combine in a
chemical reaction, the hydrogen and oxygen atoms do not
just mix together they become joined to one another
...

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2004

Contents

8E Atoms and Elements
What are atoms and elements?
Symbols for elements
Elements in the periodic table
Making compounds
Chemical reactions
Summary activities
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© Boardworks Ltd 2005
2004

Glossary
atom – The smallest particle that can exist on its own
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element – Substance made up of only one type of atom
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molecule – Two or more atoms that are chemically
joined together
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symbol – One or two letters that represent an element

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