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The History of the
Modern Periodic
Table
During the nineteenth century, chemists
began to categorize the elements
according to similarities in their
physical and chemical properties.
This is what led to out modern
Periodic Table
Johann Wolfgang Döbereiner
1829
• Grouped known elements into families of triads.
• The elements in a triad had similar chemical
properties and orderly physical properties.
• Li
Ca
S
Cl
Mn
Na
Sr
Se
Br
Cr
K
Ba
Te
I
Fe
John Newlands
In 1863, he suggested that elements be arranged in
“octaves” because he noticed (after arranging the
elements in order of increasing atomic mass) that
certain properties repeated every 8th element.
1838 - 1898
Law of Octaves
Dmitri Mendeleev
In 1869 he published a table of the elements
organized by increasing atomic mass.
Considered the Father of the Periodic Table.
1834 - 1907
• Grouped elements on
the basis of similar
chemical properties.
• Left blank spaces
to add new
elements where
he predicted they
would occur.
Accepted minor inversions when placing
the elements.
Predicted properties for undiscovered
elements, allowing for his theories to be
tested.
Mendeleev’s Periodic Table
Henry Moseley
In 1913, through his work with X-rays, he
determined the actual nuclear charge
(atomic number) of the elements. He
rearranged the elements in order of
increasing atomic number.
1887 - 1915
After co-discovering 10 new elements, in
1944 he moved 14 elements out of the main
body of the periodic table to their current
location below the Lanthanide series.
These became known
as the Actinide series.
Glenn T. Seaborg
1912 - 1999
Why We Use the Periodic
Table:
• Identify elemental characteristics
• Classify all matter
• Predict reactions between elements
Elemental Characteristics
The Periodic Table shows:
• Protons, neutrons, and electrons
• Class order and valence shell
electrons
• Average mass of elements
(mass number)
Periodic Table Geography
Periodic Law
When elements are arranged in
order of increasing atomic
number, there is a periodic
pattern in
their physical
and chemical
properties.
NONMETALS
METALLIODS
METALS
Metals, Nonmetals, & Metalloids
Periodic tables have a “stair step
line” which allows you to identify
which elements are metals,
nonmetals and metalloids.
Metals
• Most elements
are metals.
• Elements to the
left of the stair
step line are
metals or metal
like elements.
Physical Properties of Metals:
• Luster (shininess)
• Good conductors of
heat and electricity
• High density
(heavy for their size)
Physical Properties of Metals:
• High melting point
• Ductile (most metals can be
stretched into thin wires)
• Malleable (most metals can
be hammered into thin sheets)
Chemical Properties of Metals:
• Easily lose electrons
• Corrode easily. Corrosion is a gradual
chemical reaction that wears away metal.
(Example: silver tarnishing and iron rusting)
Nonmetals
• Nonmetals are found to the right
of the stair step line. Their
characteristics are opposite of
metals.
Physical Properties of
Nonmetals:
•
•
•
•
•
•
•
No luster (dull appearance)
Poor conductor of heat and electricity
Brittle (breaks easily)
Not ductile
Not malleable
Low density
Low melting point
Chemical Properties of Nonmetals:
• Tend to gain electrons.
• Since metals usually lose electrons and
nonmetals tend to gain electrons, they
like to form compounds with each
other.
• These compounds are called ionic
compounds.
• When two or more nonmetals bond
with each other, they form a covalent
compound.
Metalloids
• Elements on both sides of the
“stair step line” have properties of
both metals and nonmetals. These
elements are called metalloids.
Physical Properties of
Metalloids:
•
•
•
•
•
Solids
Can be shiny or dull
Ductile
Malleable
Conduct heat and electricity better than
nonmetals but not as well as metals
Periods and Groups
• Sizes of the atoms decrease as we
move from left to right across a period.
• This is due to the increasing number of
protons in the nucleus, so the electrical
attraction between the nucleus and the
orbiting electrons gets stronger and
pulls the electrons closer to the nucleus
Atomic Size
Periods
The horizontal rows of the periodic table
are called PERIODS.
Periods
• The elements in a period are not alike
in properties.
• The first element in a period is always
an extremely active solid. The last
element in a period, is always an
inactive gas.
• Are arranged horizontally across the
periodic table (rows 1-7)
Periods Continued
• The period number of an element
signifies the highest energy level an
electron of that element occupies.
• The elements in the same period
have the same number of valence
shells. (outermost path of an
electron)
The elements in any
group of the periodic
table have similar
physical and chemical
properties.
The vertical columns of the periodic table
are called GROUPS or FAMILIES.
Families on the
Periodic Table
• Families may be one column, or
several columns put together.
• Families have names rather than
numbers. (Just like your family
has a common last name.)
Hydrogen
Hydrogen
• Hydrogen is in its own
family.
• A diatomic, reactive gas.
• Simplest and lightest of
all elements.
Hydrogen
• Extremely flammable.
It is what the sun uses
to create light and heat.
• Hydrogen is promising
as an alternative fuel
source for automobiles
Alkali Metals
Alkali Metals
• 1st column on the periodic
table (Group 1) not
including hydrogen.
• Most reactive metals.
• Soft enough to cut with
a butter knife
Alkali Metals Continued
• They react violently with water.
• Alkali metals are never
found as free elements
in nature. They are
always bonded with
another element.
Alkaline Earth Metals
Alkaline Earth Metals
• Second column on the
periodic table.
(Group 2)
• Reactive metals that
are always combined
with nonmetals in
nature.
Alkaline Earth Metals
• They have two valence electrons.
• Several of these elements are
important nutrients for people
(such as Mg and Ca)
What does it mean to be
reactive?
• Reactive elements bond easily
with other elements to form
compounds.
• Some elements are only found
in nature bonded with other
elements.
What makes an element
reactive?
• An incomplete valence electron
level.
• The “Octet Rule” states that atoms will
gain, lose or share electrons to have the
same number of electrons as their
nearest noble gas.
• Exceptions: Hydrogen, Beryllium,
Boron
What makes an element
reactive?
• Atoms bond until this level is
complete.
• Atoms with few valence electrons,
lose during bonding.
• Atoms with 6 or 7 valence electrons
bond to gain electrons.
Transition Metals
Transition Metals
• The compounds of transition metals are
usually brightly colored and are often
used to color paints.
• Have 1 or 2 valence electrons, which
they lose when they form bonds.
Transition Metals
• They have similar properties to each
other and other metals, but their
properties do not fit any other family.
• Many combine chemically with oxygen
to form compounds called oxides.
Transition Metals
• These are the metals you are
probably most familiar with:
copper, tin, zinc, iron, nickel,
gold, and silver.
• They are good conductors of
heat and electricity.
These elements are also called
the Inner Transition Metals.
Rare Earth Elements
Rare Earth Elements
• These thirty elements make the
lanthanide and actinide series.
• Lanthanides are naturally
occurring heavy metals, used
to date rocks from outer space
and used in lasers.
Rare Earth Elements
• All Actinides are dangerously
radioactive.
• Only two occur in nature – the rest
are made in nuclear reactors and
particle accelerators. They decay
or break down very quickly.
Boron Family
Boron Family
• The Boron Family is named after the
first element in the family.
• Atoms in this family have 3 valence
electrons.
Boron Family
• This is the only
metalloid in the family,
the rest are metals.
• This family includes the
most abundant metal in
the earth’s crust
(aluminum).
Carbon Family
Carbon Family
• Atoms of this family have 4 valence
electrons.
• This family includes a non-metal,
carbon, metalloids, and metals.
Carbon Family
• The element carbon is called the
“basis of life.” There is an entire
branch of chemistry devoted to
carbon compounds called organic
chemistry.
Nitrogen Family
Nitrogen Family
• The nitrogen family is
named after the element
that makes up 78% of
our atmosphere.
• This family includes
non-metals, metalloids,
and metals.
Nitrogen Family
• Atoms in the nitrogen family
have 5 valence electrons. They
tend to share electrons when they
bond.
• Other elements in this family are
phosphorus, arsenic, antimony,
and bismuth.
Oxygen Family
Oxygen Family
• Atoms of this family have
6 valence electrons.
• Most elements in this family
share electrons when bonding.
• Oxygen is the most abundant element in the
earth’s crust. It is extremely reactive and
combines with almost all elements.
Halogens
Halogen Family
• The elements in this family are fluorine,
chlorine, bromine, iodine, and astatine.
• Halogens have 7 valence electrons, this is
why they are the most reactive non-metals.
They are never found free in nature.
• They react with alkali metals to form salts.
Halogen Family
• Halogen atoms
only need to gain
1 electron to fill
their outermost
energy level.
Noble Gases
The Noble Gases
• Noble Gases are colorless
gases that are extremely
un-reactive.
• They are inactive because
their outermost energy
level is full.
• Noble gasses are called “inert” because
they do not easily combine with other
elements.
• Noble gases include: helium, neon,
argon, krypton, xenon and radon.
• All the noble gases are found in small
amounts in the earth's atmosphere.