The Periodic Table
1) History – Mendeleev
2) Element squares
3) Atomic Number
4) Atomic Mass
5) Valence Electrons
6) Metals/Non-Metals and
Metalloids
7) Groups and Families
8) Periods
Meet the Elements
Why is the Periodic Table
Important?
• It’s a useful tool for chemists
• The periodic table organizes all the
known information about the
elements
Before the periodic table,
chemistry …
• was a mess!
• The elements weren’t organized in
any kind of logical way
• It was difficult to find information
• Chemistry didn’t make sense
Mendeléev
• The first accepted version of the
periodic table was created in 1869
by Dmitri Ivanovitch Mendeléev
• He grouped elements according to
their atomic mass, and as he did, he
found that the families had similar
chemical properties
• His understanding was so advanced
that he left blank spaces for
elements he knew would be there
but weren’t yet discovered
The Current Periodic Table
• Mendeleev was very close
• He organized the elements by atomic mass.
Today, we place them in rows by increasing
atomic number
• The horizontal rows are called periods and are
labeled from 1 to 7
• The vertical columns are called groups are
labeled from 1 to 18
The Elements
• There are 118 elements, 98 of
which occur naturally
• The remainder have been
created in the lab
• The universe as we know it is
created out of these elements
and nothing else however,
there may be others we
aren’t yet aware of
The Periodic Table
• The periodic table organizes the elements in a
particular way. A great deal of information about an
element can be gathered from its position in the
period table.
• For example, you can predict with reasonably good
accuracy the physical and chemical properties of
the element
• You can also predict what other elements a
particular element will react with chemically.
Atomic Numbers
Elements are organized on
the table according to
their atomic number,
usually found near the top
of the square.
What does each square tell us?
Different periodic tables can
include various bits of
information, but usually
include the
– atomic number
– symbol
– atomic mass
– state of matter at room
temperature
Atomic Number
• Refers to how many
protons an atom of
that element has
• No two elements
have the same
number of protons
Atomic Mass
• Atomic Mass refers
to the “weight” of
the atom
• It is found by
adding the number
of protons and the
number of neutrons
An atom’s mass is measured in
Atomic Mass Units (AMU)
• 1 AMU is very small
• There are 6 X 1023 or
600,000,000,000,000,000,000,000 AMUs in
one gram
• (Recall: Protons and Neutrons = 1 AMU,
Electrons = 1/2000 AMU)
– Since electrons contribute so little to the overall
mass of an atom, they are simply ignored
Valence Electrons
• The number of valence electrons an atom
has may also appear in a square
• Valence electrons are the electrons in the
outer energy level of an atom
• These are the electrons that are transferred
or shared when atoms bond together
Metals, Non-Metals, and
Metalloids
Use the handout to colour your top periodic table like this.
Make sure you include a legend
Properties of Metals
• Metals are good conductors
of heat and electricity
• Metals are shiny
• Metals are ductile (can be
stretched into thin wires)
• Metals are malleable (can be
pounded into thin sheets)
• A chemical property of metal
is its reaction with water,
which results in corrosion
Properties of Non-Metals
• Non-metals are poor
conductors of heat and
electricity
• Non-metals are not ductile
or malleable
• Solid non-metals break
easily.
• They are dull
• Many non-metals are gases
Properties of Metalloids
• Metalloids (metal-like) have
properties of both metals
and non-metals.
• They are solids that can be
shiny or dull.
• They conduct heat and
electricity better than nonmetals but not as well as
metals.
• They are ductile and
malleable.
Silicon is used in many
computer chips
Columns and Families
• Elements in the periodic
table are group into 18
columns
• Each element within a
column or group contains
the same number of
valence electrons
– This results in them having
similar properties
Columns and Families
• Some of these columns are
further divided into special
families
• Elements in each family
have similar but not
identical properties.
• For example, lithium (Li),
sodium (Na), potassium (K),
and other members of
family IA are all soft, white,
shiny metals.
Hydrogen
• The hydrogen square sits atop
Group 1, but it is not a member
of that family. Hydrogen is in a
class of its own.
• It’s a gas at room temperature.
• It has one proton and one
electron in its one and only
energy level.
• Hydrogen only needs 2
electrons to fill up its valence
shell.
Assign Hydrogen a colour and use the
second periodic table to colour it in.
**Include it on your legend**
Alkali Metals
• The alkali family is found in the
first column of the periodic
table.
• Atoms of the alkali metals have
a single electron in their
outermost level
• They are shiny, soft and have
the consistency of clay
• They react violently with water
and so are never found free in
nature.
Sodium metal
Assign alkali metals a colour and use
the second periodic table to colour it
in. **Include it on your legend**
Alkaline Earth Metals
• They are very reactive but
not as reactive as group 1
• They have two valence
electrons.
• Alkaline earth metals
include magnesium and
calcium, among others.
Assign alkali metals a colour and use
the second periodic table to colour it
in. **Include it on your legend**
Magnesium metal
strip
Transition Metals
• These are the metals you are
most familiar with: copper,
tin, zinc, iron, nickel, gold,
and silver
• For many, their number of
valence electrons is variable
(changes)
• They are good conductors of
heat and electricity
Assign transition metals a colour and
use the second periodic table to colour
it in. **Include it on your legend**
Halogen Family
• The elements in this
family are fluorine,
chlorine, bromine,
iodine, and astatine
• Halogens have 7 valence
electrons, and are very
reactive, therefore, they
are never found free in
nature
Assign halogens a colour and use the
second periodic table to colour it in.
**Include it on your legend**
Chlorine gas (Cl2)
contains two
chlorine atoms
bonded together
and is poisonous
Nobel Gases
• Noble Gases are colorless
gases that are extremely unreactive
• They are inactive because
their outermost energy level
is full
• The family of noble gases
includes helium, neon,
argon, krypton, xenon, and
radon.
• All the noble gases are
found in small amounts in
the earth's atmosphere.
Assign nobel gases a colour and use
the second periodic table to colour it
in. **Include it on your legend**
Helium is lighter
than air. This
allows balloons
filled with it to
float.
Rare Earth Elements
• The thirty rare earth elements are composed of the
lanthanide and actinide series
• Most are synthetic or man-made
• Look at your periodic table and determine where they
should be
Assign rare earth elements a colour and use the second periodic
table to colour it in. **Include it on your legend**
Rows and Periods
• Elements in the periodic
table are also grouped
into rows or periods
– The periods are
numbered 1-7
• Elements within a
period do not share
common characteristics
– This is because they each
have a different number
of valence electrons