Periodic Table Physical Properties Students will understand the development of the periodic table as a function of properties of the elements.

What do these random squiggles have in common?

53 known elements in 1828 How many ways can these be organized? FeCuC Pb Ag S As Sn H Ni Sb Bi Pt Cl Co Zn Hg Al Si W Os Ir Nb Se Te Br U Mn I Na F Ce Au Zr Y Cr Cd P Li B Mo Sr Ti Ba Rb K O Mg Ca Ta Be Pd N

Discovery of Elements - Until 1828 Up to 1200 a.d., only 9 elements were known…any ideas? 3 new elements found from a.d. 2 from from each from and New total: 53 Elements Discovered BC AD

In 1828, Johann Wolfgang Dobereiner developed triads These are groups of three elements containing similar traits with the atomic weight of the middle element the average of the other two. Li Na K Ca 40 Sr 87 Ba 137 S Se Te (3 + 19) / 2 = 11 = Na( ) / 2 = 87 = Sr ( ) / 2 = 34 = Se

The Law of Octaves “The eighth element, starting from the given one, is a kind of repetition of the first, like the eighth note of an octave of music.” -- John Newlands

1869- The Periodic Law The physical and chemical properties of the elements are periodic functions of their atomic weights. Introduced by Dmitri Mendeleev - “father of the periodic table” Arrange by atomic mass

Mendeleev’s Periodic Table (original publication)

A Periodic Table of Elements Based on Mendeleev’s Periodic Law

Mendeleev predicted the existence and properties of several elements unknown at his time. He was wicked smart. Mendeleev's Predictions about Eka-Aluminum: Atomic weight:about Boiling Point:low30° C Density: Formula of Oxide:EkaAl 2 O 3 Ga 2 O 3 Formula of chloride:EkaAlCl 3 GaCl 3 Chemistry of hydroxide:EkaAl ( OH ) 3 Ga ( OH ) 3

Mendeleev attributed these discrepancies to inaccurate measurements of atomic weights. New determinations confirmed the atomic weights of the elements that were predicted. The problem of reversed pairs still existed. USING SUPER X-RAY VISION!! TO... DETERMINE ATOMIC NUMBER!!

Henry Moseley … developed the idea of atomic numbers to arrange the elements. This solved the riddle of the discrepancies in Mendeleev’s Periodic table.

Modern Version of the Periodic Law The properties of the elements are periodic functions of their atomic numbers. There are 18 groups or families in the periodic table He Ne Ar Kr Xe Rn C Si Ge Sn Pb B Al Ga In Tl Be Mg Ca Sr Ba Ra H Li Na K Rb Cs Fr

There are 7 periods in the periodic table >

Physical Appearance of Elements in Groups What trends in physical appearance are exhibited by the halogens? What about the noble gases? What trends are exhibited by the alkali metals?

The periodic table is an ordered logical arrangement of the chemical elements into groups with similar properties.

“For over 100 years, The Periodic Table seems to have been the favorite toy of chemists. They have changed its form, rearranged its elements, simplified it and made it more complicated.” Zmaczynski’s Periodic Table

From the 19th Century Physicist’s Stowe Table Benfrey’s Table