Matter: Atoms, elements, molecules, compounds.

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Matter
Atoms, Elements,
Molecules,
Compounds

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Matter
• Matter is the “stuff” that all objects and
substances in the universe are made of.
• Because all matter takes up space (has
volume) and contains a certain amount
of material (has mass), all matter can be
detected and measured.

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Matter
• You can observe some types of matter
easily with your senses.
• You can see and feel things like rocks,
trees, bicycles, and different kinds of
animals.
• You can also see and smell things like
smoke and fire.

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Matter
• Other types of matter are harder to detect.
They can be observed by using a
microscope.
• Another example of matter that is hard to
detect if air, the invisible gas that surrounds
you. You can’t see or smell it, but you know it
exists. You can feel it when the wind blows
and see it bend the branches of trees.
• Regardless of what kind of matter you have,
all matter is made up of a combination of
different elements from the periodic table.

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How many different substances are there?
There are millions of different substances!
What are they all made of?
How many
different substances
can you think of?

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All substances are made of atoms
All substances are made of very tiny particles called atoms.
hydrogen and
oxygen atoms
carbon and
hydrogen atoms
carbon, nitrogen,
hydrogen, oxygen
and sulphur atoms
iron, aluminium,
silicon, oxygen
and boron atoms
Many substances are made up of different types of atoms.

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What is an element?
All substances are made of very tiny particles called atoms.
The elements are the simplest substances in the universe.
The elements are the building blocks of all other substances.
copper
carbon
There are about one hundred substances that are made up
of just one type of atom. These are the elements.
helium

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An element is a substance made up of only one type of atom.
Atoms in elements
Copper is an
element made up of
copper atoms only.
Carbon is an
element made up of
carbon atoms only.
Helium is an
element made up of
helium atoms only.

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Atoms and molecules of elements
Contents
In some elements, the atoms are joined in groups of two or
more. A particle containing atoms grouped in this way is
called a molecule.
An element is a substance made up of only one type of atom.
Other elements, that contain atoms joined in molecules are
hydrogen, nitrogen, chlorine and bromine.
Oxygen is an
element made up of
oxygen atoms only.
How many atoms
are there in an
oxygen molecule?

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The symbol for many of the more common elements uses
just the first letter of the name.
Introducing chemical symbols
A standard set of symbols is used to represent elements:
hydrogen
H =
carbon
C =
fluorine
F =
oxygen
O =
nitrogen
N =
Others elements have
the first two letters.
lithium
Li =
aluminium
Al =
helium
He =
Some of the symbols are not
always as you might expect.
lead
Pb =
gold
Au =
silver
Ag =
iodine
I =

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How to write symbols for elements
Two important rules should be followed when writing the
symbols of elements so that there is no confusion.
1. The first letter of an element’s symbol is always
a capital letter.
2. If there are two letters in the element’s symbol,
the second letter is always a small letter.
e.g. N (not n) for nitrogen
e.g. Co (not CO) for cobalt
No, Watson! It was
carbon monoxide
poisoning – not cobalt.

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In some elements, the atoms are joined together and
form molecules. Combining the symbols of the atoms
in a molecule gives you the formula of the molecule.
What is the formula for the molecules in each element?
Symbols for molecules of elements
nitrogen
oxygen
N2
O2
There are
groups of
two atoms
in each
molecule.

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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.
Non-metals are
mostly on the right.
Metals are on the
left and in the centre.
What type of elements are between metals and non-metals?
Xe

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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.
In a similar way, a small number of elements can be
combined in many different ways to make a huge
number of different compounds.

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What is a compound?
A compound is the substance produced when two or more
elements combine in a chemical reaction.
A compound is always made up of two or more
different types of atom.
Two elements, hydrogen (H)
and oxygen (O), combine to
make the compound, water.
Which two elements combine
to make the compound
carbon dioxide?

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Making a compound – carbon dioxide
A compound has very different properties to the elements
from which it is made.
carbon dioxide
A colourless gas
which is used
to put out fires.
to make
carbon
A black solid
which can be
used as a fuel.
combines
with
compound
elements
oxygen
A colourless gas
which is essential
for life.

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Making a compound – water
What are the elements which make up water?
In what ways are the elements different to their compound?
to make
combines
with
compound
elements
water
A liquid which is
essential to our
lives and has many
different uses.
hydrogen
A colourless gas
which is used in
hot air balloons.
A colourless gas
which is essential
for life.
oxygen

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Element or compound?

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Element or compound?

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When the two elements, hydrogen and oxygen, combine in a
chemical reaction,
Atoms joining in a chemical reaction
In a chemical reaction, the atoms in the reactants
become joined in different ways and this is how
new substances are formed.
hydrogen oxygen water
+
+
H H
H H
O O
the hydrogen and oxygen atoms do not
just mix together they become joined to one another.

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Glossary
atom – The smallest particle that can exist on its own.
compound – Substance made up of two or more
different elements that are chemically joined together.
element – Substance made up of only one type of atom.
formula – The symbols and numbers that represent the
atoms in a substance.
molecule – Two or more atoms that are chemically joined
together.
periodic table – Table in which all known elements are
arranged based on their properties.
symbol – One or two letters that represent an element.

Matter: Atoms, elements, molecules, compounds.

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