Table 2 represents the (slightly enhanced) facts about the chemical elements as known to Mandeleev in 1868. The instructor must provide each student (or group of students) with a pile of index cards. Each card should contain the data from one of the cells, possibly formatted as in Figure 1. The card pile should have 67 different cards representing every element known to Mandeleev. After a little introduction (triplets and octets section below), ask the students to arrange the cards in some order that will enhance our understanding about the elements. Since the students probably know about the periodic table already, they should be able to arrange the cards quickly. Then ask them to devise some interpretations and uses for the table as it existed in Mendeleev's era.
Triplets and Octets
In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads (groups of three) based on their chemical properties. Lithium, sodium, and potassium, for example, were grouped together as being soft, reactive metals. Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third. This became known as the Law of Triads.
English chemist John Newlands produced a series of papers in 1864 and 1865 that described his own classification of the elements: he noted that 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 This Law of Octaves, however, was ridiculed by his contemporaries, and the Chemical Society refused to publish his work. Nonetheless, Newlands was able to draft an atomic table and use it to predict the existence of missing elements, such as germanium. The Chemical Society only acknowledged the significance of his discoveries some five years after they credited Mendeleev.
Symbol: F Name: Florine Atomic Weight: 19 Properties: Halogen |
Figure 1. Card format for each card in the deck.
The properties are indicated by a single word and the instructor should provide the definition of each of the words as listed below:
H Hydrogen 1 Hydrogenic |
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Li Lithium 7 Alkali metal |
Be Beryllium 9.4 Alkaline earth metal |
B Boron 11 Metaloid |
C Carbon 12 Non-metal |
N Nitrogen 14 Non-metal |
O Oxygen 16 Non-metal |
F Fluorine 19 Halogen |
|
Na Sodium 23 Alkali metal |
Mg Magnesium 24 Alkaline earth metal |
Al Aluminum 27.3 Post-transition metal |
Si Silicon 28 Metaloid |
P Phosphorus 31 Non-metal |
S Sulfur 32 Non-metal |
Cl Chlorine 35. Halogen |
Fe Iron 56, Transition Metal |
K Potassium 39 Alkali metal |
Ca Calcium 40 Alkaline earth metal |
? ? 44 Transition Metal |
Ti Titanium 48 Transition Metal |
V Vanadium 51 Transition Metal |
Cr Chromium 52 Transition Metal |
Mn Manganese 55 Transition Metal |
Co Cobalt 59 Transition Metal |
Cu Copper 63 Transition metal |
Zn Zinc 65 Transition Metal |
? ? 68 Post-transition metal |
? ? 72 Metaloid |
As Arsenic 75 Metaloid |
Se Selenium 78 Non-metal |
Br Bromine 80 Halogen |
Ni Nickel 59 Transition Metal |
Rb Rubidium 85 Alkali metal |
Sr Strontium 87 Alkaline earth metal |
?Yt Yttrium 88 Transition metal |
Zr Zirconium 90 Transition metal |
Nb Niobium 94 Transition metal |
Mo Molybdenum 96 Transition metal |
? ? 100 Transition Metal |
Ru Ruthenium, 104 Transition metal |
Ag Silver 108 Transition metal |
Cd Cadmium 112 Transition metal |
In Indium 113 Post-transition metal |
Sn Tin 118 Post-transition metal |
Sb Antimony 122 Metaloid |
Te Tellurium 125 Metaloid |
J Iodine 127 Halogen |
Rh Rhodium 104 Transition metal |
Cs Cesium 133 Alkali metal |
Ba Barium 137 Alkaline earth metal |
?Di ? 138 Lanthanide |
?Ce Cerium 140 Lanthanide |
Pd Palladium 106 Transition metal |
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?Er Erbium 178 Lanthanide |
?La Lanthanum 180 Lanthanide |
Ta Tantalum 182 Transition metal |
W Tungsten 184 Transition metal |
Os Osmium, 195 Transition metals |
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Au Gold 199 Transition metal |
Hg Mercury 200 Transition metal |
Tl Thallium 204 Post-transition metal |
Pb Lead 207 Post-transition metal |
Bi Bismuth 208 Post-transition metal |
Ir Iridium, 197 Transition metals |
Pt Platinum 198 Transition metals |
|
Th Thorium 231 Actinide |
U Uranium 240 Actinide |
Table 2. This table represents the knowledge of the elements as known to Mandeleev in 1861.
Just for fun, here is Mandeleev's original table.