How to Read the Periodic Table

A periodic table is a table that displays chemical elements, their properties, and their trends. The currently used periodic table was designed by D. Mendeleev. Element symbols are arranged in rows, from left to right, and from top to down, with increasing atomic number (the top number when looking at the element symbol): 

When looking at a specific element symbol, for example, the carbon in the picture above, the top number is called the atomic number and is always an integer, the bottom number is the average atomic mass of the element in atomic mass units (amu) and the middle letter is the element’s symbol. Some periodic tables will also include the full name of the element.  

The structure of the periodic table communicates several chemical properties about the elements displayed. Some important definitions to know are that the row of the periodic table is called a period, and the column of the periodic table is called a group. Also, some of the groups have specific names. The first group (column) is called the alkali metals group (however, it does not include hydrogen). The second group is called alkaline earth metals. Groups 3 through 12 are called transition elements. Group 17 is called halogens and the last group 18 is called noble gasses.