0.1.4: Review of Periodic Trends

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A Note from Dr. Haas: In this course, we will rely a lot on knowing two main types of information when it comes to periodic trends. You will need to know when to apply knowledge of general trends and when to apply knowledge of the exceptions.

General periodic trends: These are patterns that exist in the periodic table, patterns that allow you to predict properties of atoms and ions based on where a given element lies on the table. These are also called "general trends".
Exceptions: Several elements do not follow the general trends, particularly the elements in the d- and f-blocks of the periodic table. There are still some patterns that can be used to predict their properties, but they are outliers in the general trends. Oftentimes these elements are said to be exceptions to the rule or to have unusual properties.

Please read the following subsections to review general periodic trends.

Introduction

General periodic trends are specific patterns that are present within the periodic table; these are patterns in properties like electronegativity, ionization energy, electron affinity, atomic radius, melting point, and metallic character. General periodic trends arise from the arrangement of the elements on the periodic table; this arrangement was originally based on physical properties of the elements and we now know that properties are related to electron configuration.

General periodic trends provide chemists with an invaluable tool to quickly predict an element's properties. These trends exist because of the similar atomic structure of the elements within their respective group families or periods and because of the periodic nature of the elements.

The general periodic trends that are most relevant for this course are described further below.