HISTORY OF THE PERIODIC
TABLE
Antoine Lavoisier
In 1789, he published a
list of elements that
had 33 elements
Johann Wolfgang Dobereiner
Came up with the idea of
Law of Triads – noticed
that elements of 3 had
similar traits, such as:
• chlorine, bromine, and
iodine
• calcium, strontium, and
barium
• sulfur, selenium, and
tellurium
• lithium, sodium, and
potassium
Classification of Elements
Spiral Table, “Vis Tellurique” (1862)
Law of Triads (1829)
http://image.wistatutor.com/content/feed/u80/Newlands_periodiska_system_1866.png
John Newland
Law of Octaves – When
listed in order of
increasing atomic weight,
similar physical and
chemical properties
recurred at intervals of
eight, which he likened to
the octaves of music
Classification of Elements
Law of Octaves (1865)
Which table makes more sense?
Julius Meyer (1870) and Dmitri Mendeleev
(1869) – both listing the elements in a row or
column in order of atomic weight and starting
a new row or column when the characteristics
of the elements began to repeat .
Since both Meyer and Mendeleev published their
periodic tables about the same time and using
similar techniques, why do you think
Mendeleev got credit for being “the father of
the modern periodic table?”
Dmitri Mendeleev
• Organized his periodic table
with increasing atomic mass
• Switched adjacent elements,
such as cobalt and nickel, to
better classify them into
chemical families
• He left gaps in his periodic
table
– Predicted the physical and
chemical properties of those
undiscovered elements
Arranged
periodic table
according to
Atomic Mass
Developing the Periodic Table
Mendeleev (1869)
• Arranged elements according to atomic mass
• Chemical properties repeated in intervals
• Predicted chemical properties of
undiscovered elements
Henry Moseley
1914 – found a relationship
between an element's Xray wavelength and its
atomic number (Z),
rearranged the table by
nuclear charge rather than
atomic weight
Henry Moseley
Developing the Periodic Table
Moseley (1911)
• Determined elements fit patterns better if
arranged by atomic number
Periodic Law
• Physical and chemical properties are periodic
(reoccurring) when elements are arranged by
their atomic number
Increase in Atomic Number as you go across a period
13 14 15 16 17 18
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
How to read the P.T.
13 14 1
5
3
4
5
6
7
8
9
10 11 12
16 17 18
13 14 1
5
3
4
5
6
7
8
9
10 11 12
16 17 18
Column = Group
13 14 1
5
3
4
5
6
7
8
9
10 11 12
16 17 18
Column = Group
13 14 1
5
3
4
5
6
7
8
9
10 11 12
16 1
7
18
Let’s look for Oxygen
8
O
Oxygen
15.994
Element
Period
Group
3
13
4
9
6
18
Oxygen (O)
Barium (Ba)
Iron (Fe)
Gold (Au)
Bromine (Br)
Cesium (Cs)
17
6
13 14 1
5
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
16 17 18
13 14 1
5
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
16 17 18
13 14 1
5
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
16 17 18
13 14 1
5
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
16 17 18
Barium (Ba)
13 14 1
5
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
16 17 18
Barium (Ba)
13 14 1
5
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
16 17 18
Barium (Ba)
13 14 1
5
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
16 17 18
Element
Period
Group
Oxygen (O)
2
16
Barium (Ba)
6
2
3
13
4
9
6
18
Iron (Fe)
Gold (Au)
Bromine (Br)
Cesium (Cs)
17
6
Iron (Fe)
13 14 1
5
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
16 17 18
Iron (Fe)
13 14 1
5
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
16 17 18
Iron (Fe)
13 14 1
5
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
16 17 18
Element
Period
Group
Oxygen (O)
2
16
Barium (Ba)
6
2
Iron (Fe)
4
8
3
13
4
9
6
18
Gold (Au)
Bromine (Br)
Cesium (Cs)
17
6
Element
Period
Group
Oxygen (O)
Chlorine (Cl)
Calcium (Ca)
Gold (Au)
2
16
3
4
6
13
9
18
17
Bromine (Br)
Cesium (Cs)
6
Element
Period
Group
Oxygen (O)
Chlorine (Cl)
Calcium (Ca)
Gold (Au)
Aluminum (Al)
Cobalt (Co)
Radon (Rn)
Bromine (Br)
Cesium (Cs)
2
3
4
6
3
4
6
4
6
16
17
2
11
13
9
18
17
1
Navigating the Table
Column = Group
13 14 15 16 17 18
n=1
n=2
n=3
3
4
5
6
7
8
9
10 11 12
n=4
n=5
n=6
n=7
• Elements in families have similar physical and chemical
characteristics because they have the same number of
valence electrons (i.e. similar electron configurations).
Valence Electrons
 Electrons in the highest (outer) electron level
 Have most contact with other atoms
 Known as valence electrons
 Outer shelI of noble gases the outer shell contains 8
valence electrons (except He = 2)
Octet Rule
 An octet in the outer shell makes atoms stable
 Electrons are lost, gained or shared to form an octet
 Unpaired valence electrons strongly influence bonding
• All of the elements on the periodic table fall into one
of four major categories:
– Metals (to the left of the stair-step line) are generally solids
at room temperature, they are good conductors of heat
and electricity, they are generally shiny (i.e. lustrous),
ductile and malleable.
– Non-metals (to the right of the stair-step line) can be solids,
liquids, or gases at room temperature. They are very poor
conductors of heat and electricity. They are generally
brittle if solid, rather than being ductile and malleable.
They are generally non-lustrous.
– Semi-metals or metalloids (bordering the stair-step line
EXCEPT aluminum) have characteristics of both
metals and nonmetals. They are usually good semiconductors (i.e. they conduct heat and electricity only
at very high or very low temperatures).
– Noble gases comprise the last vertical column in the
periodic table. They are all gases at room
temperature. They are very unreactive (i.e. inert)
because they have full s and p orbitals (i.e. the stable
octet, or stable duet in the case of helium).
• In addition, there are also several families
(columns) that have unique names and
properties.
Alkali metals
• Alkali metals (first
group).
• Only have one
valence electron.
• React violently with
water producing
alkaline solutions (i.e.
pH>7)
Alkaline Earth metals
• Alkaline Earth metals
(second group).
• Have two valence
electrons.
• Also react with water
to produce alkaline
solutions, though
much less violently.
Transition Metals
• Transition metals are the
d block elements.
• These elements are good
conductors of electricity
and have a high luster.
They are typically less
reactive than alkali and
alkaline earth metals.
– Some are so unreactive
that they don’t form
compounds and exist in
nature as free elements.
Lanthanides
• Lanthanides are the first row of the f block –
they are named after the first element in the
row, lanthanum.
• They are shiny metals similar in reactivity to
the group 2 metals.
Actinides
• The actinides are the second row of the f
block – they are named after the first
element in the row, actinium.
• All actinides are radioactive; the first four
(Th through Np) are naturally occurring; all
others have been created artificially.
Halogens
• Halogens
(seventeenth group).
• Contain seven valence
electrons.
• Pair very nicely with
alkali metals of group
1.
Noble Gases
•
•
•
•
Noble gases (last group).
Contain eight valence electrons
– satisfy the octet rule. (He,
however, only has 2 valence
electrons.)
In a chemical reaction, these
elements will not lose or gain
electrons because they have
already achieved stability.
Since they are already stable,
they will rarely react and are
called inert.
What do you notice about the valence electrons in groups 1, 2, 13-18?
13 14 15 16 17 18
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
13 14 15 16 17 18
n=1
n=2
n=3
n=4
n=5
n=6
n=7
3
4
5
6
7
8
9
10 11 12
Group
Group/Family Name
Valence
Configuration
# of Valence
Electrons
1
Alkali Metals
ns1
1
2
Alkaline Earth Metals
ns2
2
3-12
Transition Metals
It varies
It varies
13
The Boron Family
ns2np1
3
14
The Carbon Family
ns2np2
4
15
The Nitrogen Family
ns2np3
5
16
The Oxygen Family
ns2np4
6
17
Halogens
ns2np5
7
ns2np6
8
18
Noble Gases