The genius of Mendeleev’s periodic table - Lou SericoIt It became evident early in the science of chemistry that certain elements could be grouped together by the similarities of their physical properties.
In 1829, the German chemist Döbereiner, became the first to propose a relationship between atomic weights and the properties of elements.
The English chemist Newlands, in 1865, saw a correlation between the atomic weights and the properties of the elements. Mendeleev in Russia and Lothar Meyer in Germany, in 1870, working independently and unaware of Newlands, outlined this relationship in detail.
This led to a statement that the properties of the elements are periodic functions of their atomic weights. In each row the elements differ quite a bit in properties. There is, however, an interesting graduation of properties as atomic weight increases. Note that elements in a vertical column have similar properties. For example, lithium is similar to sodium.
Moseley, in 1911, showed that atomic numbers rather than atomic weights are the determining factor of chemical properties. If you check the Periodic Table you can see that argon (At. Wt. 39.948) precedes potassium (At. Wt. 39.098). There are other reversals in the table as well. This is due to the abundance of heavier isotopes of some elements. This affects the atomic weight of the element, which is an average.
The Periodic Law is: The properties of the elements are periodic functions of their atomic numbers.
For this exercise you will construct a color coded 3 dimensional representation of the periodic table. This was devised by a science exhibit designer, Roy Alexander. This is called the Alexander Arrangement of the Elements (AAE).
First you will need to color code the elements. You may use crayons, markers or highlighters. Be sure not to obscure the information on the chart.
First step is to mark the elements for which ONLY radioactive isotopes exist. You will color the metallic elements red, non-metals will get colored yellow , noble gases green. You will mark a blue slash, diagonally across the elements that are gas at room temperature, in this orientation ➚, and for the two elements that are liquid at room temperature draw a blue circle around the letters of their symbol. Draw in a stairstep like the one on your reference table, starting at Boron. You should, finally, color the metalloids (elements on either side of the stairstep line except #13, 84 & 117) orange.
After the chart is completely colored you can begin to cut out the pieces. Be sure NOT to cut off any of the marked tabs, these will be needed to connect the table to itself, properly. Remove the spaces between 56 & 72 and 88 & 104. Cut out the elements along the edges. With the paper on a table fold the 3 tabs forward and leave with approximate right angle orientations. Fold towards you.
Now you are ready to assemble your AAE. First you will tape or glue the section from the bottom. The tabs have been marked with numbers, be sure each number is behind the appropriate elements. Next bulge "B" column elements forward and squeeze the back together so that elements 12 & 13 are next to each other and the folds are next to each other. Tape along the back so that you have two loops of elements. Now you can tape column 18 to column 1, using the tab that you left attached, forming a cylinder. Be careful to twist the tube slightly, so that Helium lines up with Lithium, and all the noble gases are immediately adjacent to the alkali metal with a 1 higher atomic number. The tabs should have their numbers immediately behind the appropriate elements.
Now you should have the 3 D table, where all elements are next to the elements with 1 higher or 1 lower atomic number. The only exception is the Hydrogen, which has individual enough characteristics to warrant it being discontinuous. And now we have a fine reference tool, keepsake, and conversation piece - the Alexander Arrangement of the Elements! Color noble gases, metals, non,metals
