Periodic Table

The periodic table presents the elements arranged in atomic number order. Elements are organized in periodic groups based on the number of valence electrons of the element, and are classified as metals, nonmetals, and metalloids. It was Dmitrii Mendeleev and Lothar Meyer who created and published the first successful periodic tables in 1870, although they had worked independently of each other. Mendeleev based his table on chemical properties; Meyer, on physical properties. Mendeleev proposed a table with columns of related elements, yet his table was incomplete; he intentionally neglected to fill each space. These voids, however, eventually lead to the discovery of new elements. Put simply, Mendeleev accurately predicted the properties of the undiscovered elements, realizing the periodic relationships of the elements around them on this table. As a result, the periodic table is an organizational tool and an important source of information about each element, as well as the trends of the elements.

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INSTRUCTIONS

Elemental Properties
A variety of commonly studied properties of the elements are available for examination using this computerized periodic table. The characteristics of each element can be obtained by one of four methods:

1. Click on the element in the periodic table.
2. Type the name of the element in the text box and press return.
3. Type the element's symbol in the box and press return.
4. Type the element's atomic number in the box and press return.

The elemental properties to be examined include:

Atomic Weight	Ionization Energy	Density
Covalent Radii	Melting Point	Ionic Radii
Boiling Point	Isotopes	Electron Affinity
Common Charges	Electronegativity

Periodic Trends

• Atomic Number Graphs plot a property as a function of the atomic number for all 105 elements. To view an atomic number graph, (1) click on the Atomic Number Graphs menu item, then (2) select the property of interest.
  The atomic number vs. property graph appears in place of the periodic table. To graph a different property, click on the Atomic Number Graphs menu again and select another property.

• Graph Group menu items allow plots of elemental properties as a function of the period. These plots show trends across or down the periodic table. To make periodic plots, click on the property of interest under the Graph Group menu. Secondly, choose a period to plot by clicking on any element in the period of interest. Once again, the plot appears in place of the periodic table.