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THE PERIODIC TABLE
OF ELEMENTS
groups
8
O
Oxygen
15.999
elements
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H
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atoms
O
by J. Smith
2
6
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Before we get
started ...
What is an
element?
gold is an element
because all the atoms
in this gold bar
are individual gold atoms
An element
is something
that is made of
only one type
of atom.
ice (water) is NOT an element,
because it contains
MORE than one type of atom
(It contains hydrogen and
oxygen atoms)
O2
oxygen is an element,
because all the atoms
comprise only of oxygen atoms
Atoms are the
smallest unit of
an element.
H2
The element hydrogen
The hydrogen atom
(diagrammatic version)
What is the
Periodic Table of
Elements?
It’s a way of
organising
elements,
according to
their properties.
Elements
It’s a bit like
the way we
organise the
days of the
month in a
calendar.
Day of the Month
The vertical
column
represents
the day
of the
month.
The horizontal row
represents the
week of the month.
Week of the Month
(i.e.: First week in July)
The Periodic Table of Elements
lists (or organises) all the
chemical elements that are found in the world.
How are the
elements
organised?
Yikes!
Looks
complicated!
No it’s not!
It’s quite
elementary
actually!
and
horizontal rows
(called periods)
Horizontal Rows
vertical columns
(called groups)
Vertical Columns
Just like the calendar,
the Periodic Table
is organised into:
Just like the seasons in the year, or
the days in the year on a calendar,
the periodic table of elements has
a repeating pattern ... based on the
particles in the atoms.
Reminder:
Particles in an atom consist of 3 things:
electrons
protons
neutrons
electrons (e-)
The electrons (e- ) have a
negative electrical charge
(-1 or 1-).
nucleus
neutrons
The neutrons have
no charge,
they’re neutral.
protons
The proton have a
positive electrical charge
(+1 or 1+).
Horizontal Rows (PERIODS)
Let’s look at
the horizontal rows,
or PERIODS,
first.
horizon
horizontal
The horizontal rows (or periods)
are arranged according to the
atomic number of an element
(i.e. number of protons in an atom).
atomic number
Periods
Reminder:
electrons (e-)
An atom is made up of:
Electrons
whizzing about
in the space
around the nucleus.
The nucleus
is made up of
the protons and
the neutrons.
nucleus
neutron
protons
Atomic Number
The atomic number
is the number of
protons
in an atom.
protons
nucleus
neutrons
For example, oxygen has:
an atomic
number of 8
Period
Period
nucleus of
oxygen
+
+ + +
+ + + +
+
+
+
++ +
+ +
8 protons
8 neutrons
Remember, it is the number of protons and NOT the number of neutrons, because
the number of neutrons can vary depending on the isotope of an element.
! Reading across the periods,
the periodic table starts at
an atomic number of
1 (hydrogen - has 1 proton)
#
Then it goes to
3 (lithium has 3 protons),
4 (beryllium has 4 protons),
5 (boron has 5 protons),
etc.
" Then it goes to 2
(helium - has 2 protons)
Reading across the Period
Reading across the Period
As you move to the right (and down) the periodic table, the
number of protons (and neutrons and electrons) increase.
Reading across the Periods
-
+
The weight of the atom
will also increase
as the number of
protons increase.
hydrogen is the lightest of
all the elements as it has the
fewest protons in it
-
++
-
helium is heavier than
hydrogen because it
has more protons
The periods are
arranged in order,
based on their
atomic number
(number of protons),
from
1
to
118
Periods
Periods
There are 7 periods, or horizontal rows.
Arranged from left to right, according to atomic number
Periods
These 7 periods, or horizontal rows correspond to
the number of energy shells
(or energy levels, or electron orbits)
in the atoms.
Reminder:
energy
shells
electron
Electrons can have different
amounts of energy in an atom.
Electrons are arranged in the
atom around the nucleus in
different energy levels
(or energy shells).
Electrons with the same
energy levels are found
in the same shell.
Each shell in the atom
contains a certain
number of electrons.
electron
shell
nucleus
1st energy shell
can contain a maximum
of 2 electrons
2nd energy shell
can contain a maximum
of 8 electrons
3rd energy shell
can contain a maximum
of 18 electrons
Getting back to our
7 periods, or rows,
that show the
number of
energy shells ...
Periods
Row 1 ... only has 1 shell
Row 2 ... has 2 shells
Row 3 ...
has 3 shells
etc ...
up to Row 7
with 7 shells
d
i
l
2s
! horizontal rows ng 3
i
n
i
Periods
(called periods)
a
m
t
ew
i
v
ToArranged
e
r
he
,
s
nt
l
fE
e
em
o
e
There are 7 periods.l
b
a
Elements
in
the
according to the
T
c
m
i
o
same
period have the
atomic number
r
d
f
o
i
m
same number of
(number e
of r
e
h
"
vertical
columns
:
t
t
P
a
energy shells ad
protons
in an
,
e
s
o
h
r
l
e
(called
groups
n
T atom).
(electron w
orbits).
h
c
ea
ith
do
T
e
m
s
or
families)
S
y
a
j
a
J
e
/
l
P
e
p
r
s
o
t
r
e
S
/
h
c
m
o
a
c
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.
T There are 18 groups.
hers
c
a
e
t
y
Elements in thessame
a
p
r
e
h
group usually
have the
c
a
e
t
.
w
same
number
of electrons
w
w
/
/
:
in their
http
outer energy shell.
Groups
Summary:
n
o
The periodic table
is
es organised into:
groups
8
O
Oxygen
15.999
atoms
elements
riods
pe
H
H
e
e
c
valen
The
Periodic
Table
O
By J Smith
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