Periodic Table History

History of the Periodic Table:At the conclusion of our time together, you should be able to:1. List one of the earliest contributors to

the discovery of the elements2. Explain triads and who developed this

table of the elements3. Explain the law of octaves and who

developed this table of the elements4. Explain the first real periodic table and

who developed this table of the elements

5. Mark a period, group, and the metal, nonmetal, metalloid areas of the periodic

table

Aristotle

4 Elements

Fire, Water, Air, Earth

~350 B.C.-

14 elements were known

By 1700 -

Antoine Lavoisier wrote the first extensive list of 33 elements.

~1789-

Johann Dobereiner (German Chemist) noticed that Br, Cl, and I had similar properties and that Br’s atomic mass was between that of Cl & I.

He found three other groups with similarities. He called these groups triads.

1829 -

Cl, Br, ICa, Sr , BaS, Se, TeLi, Na, K

Other Triads of Dobereiner:

Little Known Phobias!

Baabaaphobia

Fear of being fleeced

John Newlands (English Chemist) arranged the now known 62 elements from lightest to heaviest.

He also noticed that every 8th element had similar chemical and physical properties. Their properties were repeating. This became known as Newland’s Law of Octaves.

Li Be B C N O FNa Mg Al Si P S Cl

1864 -

Dmitri Mendeleev (Russian Chemist) organized the elements by atomic mass also but made it into table form to help his students.

Elements with similar properties were put into the same column.

Considered the Father of the Modern Period Table!

1869 -

He left blanks where elements seemed to be missing.

There were places where heavier elements were put before lighter elements because of their properties:

Te – I Co – NiAr – K

(He felt the mistake was in measuring the mass and this would be corrected with further research.)

Mendeleev (cont.)

The Periodic Table

Dmitri Mendeleev (1834 - 1907)

Henry Moseley (English Chemist) arranged elements by atomic number.

This gave rise to a new Periodic Law, “Properties of elements are periodic functions of their atomic number.”

1913 -

Murphy's Lawsof

Science and Technology

Technology is dominated by those who manage what they do not understand.

Glenn Seaborg(1912-1999)

Discovered 8 new elements.

Only living person for whom an element was named.

The Language of ChemistryThe elements, their

names, and symbols are given on the PERIODIC TABLE

How many elements are there?• 117 elements have been identified• 90 elements occur naturally on Earth

• Examples: gold, aluminum, lead, oxygen, carbon• 27 elements have been created by scientists

• Examples: technetium, americium, seaborgium

Periodic Table Terminology

Period/Series = horizontal rows

Group/Family = vertical columns

MetalsLocated to the left of the staircase lineCharacteristics

Lose electrons to form + ions (cations)ShinyMalleableDuctileGood conductors of heat & electricityReact with acid

Most metallic element = Fr (francium)

NonmetalsLocated to the right of the staircase lineCharacteristics:

Tend to gain electrons to form – ions (anions)

DullPoor conductors of heat and electricityBrittle

Most reactive nonmetal = F (fluorine)

Metalloids

Located on and below the staircase line except At, Po and Al.

Characteristics:Tend to gain or lose electronsShiny and dullGood and poor conductors of heat and

electricityMalleable and brittle

History of the Periodic Table:Let’s see if you can:

1. List one of the earliest contributors to discovery of the elements

2. Explain triads and who developed this table of the elements

3. Explain the law of octaves and who developed this table of the elements

4. Explain the first real periodic table and who developed this table of the elements

5. Mark a period, group, and the metal, nonmetal, metalloid areas of the periodic

table

Where are Periods, Groups, Metals, Nonmetals, and Metalloids?

1. List one of the earliest contributors to discovery of the elements

2. Explain triads and who developed this table of the elements

3. Explain the law of octaves and who developed this table of the elements

4. Explain the first real periodic table and who developed this table of the elements

Toburen’s Attempt at a Periodic Table: