GED Science: Periodic Table

Elements have properties, just like the substances you learned about in the previous lesson.  In fact, a Russian chemist named Dimitry Mendeleev was examining the properties of a number of elements in the 1800’s. Through his observations, Mendeleev noticed that some elements shared properties in an interesting pattern.  His arrangement of the elements to reflect these patterns is our modern day periodic table.  The periodic table is an arrangement of elements that shows repeating patterns of properties.  It is an extremely important tool that allows chemists to predict: the properties of elements, which elements will combine to form compounds, the properties of those compounds, and whether or not a chemical reaction will occur.  The following is a diagram of the periodic table:


This diagram of the periodic table below shows how elements are arranged into columns, called groups, and rows, called periods. Groups are often referred to by specific names:


Elements that are in the same group exhibit similar chemical properties; for example those in group I (alkali metals) are all very chemically reactive, while elements in group 18 (noble gases) are all very stable, and chemically unreactive.  The beauty of the periodic table is that its arrangement allows you to understand a number of patterns in the properties of elements.  The following diagram shows some patterns in the elements in the periodic table:


Do not worry if you do not understand the words in the arrows in the above diagram.  The diagram is simply mean to show that many chemical properties of elements occur in patterns in the periodic table. In order to understand why this arrangement of elements shows the patterns it does, we must examine the atomic structure of the elements.


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