Electronegativity within periodic table

In the periodic table, values of electronegativities increase from left to right across a period and from bottom to top within a group. 

When comparisons are made within a column of the periodic table, it is found that electronegativity is no longer the controlling factor. Acidity increases from top to bottom in a column of the periodic table, whereas electronegativity decreases. 

Carbon, phosphorus, and iodine have about the same electronegativity. Within a row of the periodic table, electronegativity increases from left to right. Within a column of the periodic table, electronegativity increases from bottom to top. 

The nucleophilic strength of anions, within the same row of the periodic table, follows the same order as basicity the more electronegative... 

Understanding the wealth of information found in the organization of the periodic table is a central skill for general chemistry. You will always have a periodic table available for ACS exams, and likely for most classroom tests as well. Therefore, knowing the trends within the periodic table will allow prediction of properties, even for unfamiliar elements. Relative sizes of atoms and ions, trends in ionization energy, and trends in electronegativity are all important to understanding the behavior of elements. The differences between metals and nonmetals and their reactions are also based on periodic trends. Trends within families and trends within periods can both reveal much about the physical properties and chemical reactions expected for the elements. 

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