Describe the main periodic trends of the following from top...

Name: Problem 2, Chapter 11: Principles of Descriptive Inorganic Chemistry
Uploaded: 2021-06-15T18:53:50-08:00
Duration: 6 min 46 s
Channel: Susan Hallstrom
Description: Describe the main periodic trends of the following from top to bottom in the periodic table: a. electronegativity; b. radius; c. covalent-bond energy; d. common oxidation numbers. Tell in what blocks of the periodic table (if any) you find anomalous countertrends.

Describe the main periodic trends of the following from top to bottom in the periodic table: a. electronegativity; b. radius; c. covalent-bond energy; d. common oxidation numbers. Tell in what blocks of the periodic table (if any) you find anomalous countertrends.

Key Concepts

Electronegativity

Electronegativity is a measure of an atom's ability to attract electrons in a bond, and it generally decreases from top to bottom within a group due to the increase in atomic size and electron shielding. This trend is modulated by the effective nuclear charge experienced by the bonding electrons, with variations seen in different parts of the periodic table such as in transition metals where added d-electrons can alter the trend.

Atomic Radius

Atomic radius describes the size of an atom, which typically increases from top to bottom in a group as additional electron shells are added. This addition outweighs the pull of the nucleus on the outer electrons, resulting in a larger atomic size. However, anomalies may occur in certain blocks due to electron repulsion and incomplete shielding effects.

Covalent Bond Energy

Covalent bond energy refers to the energy required to break a covalent bond and is influenced by factors such as atomic size, orbital overlap, and electronegativity differences. Generally, smaller atoms with higher electronegativity form stronger bonds due to better overlap and less diffuse orbitals, though variations in orbital types across different blocks can result in countertrends.

Common Oxidation Numbers

Common oxidation numbers indicate the typical charges atoms adopt in compounds, reflecting their electron configurations and tendencies to lose, gain, or share electrons. These vary down a group due to the ease of electron removal or addition and can be significantly different in elements from different blocks, especially as transition elements may display multiple oxidation states due to their d-electron involvement.

Anomalous Periodic Trends in Specific Blocks

Anomalous trends occur primarily in the transition metal block and occasionally in the f-block, where the expected periodic trends such as changes in electronegativity, radius, or bond energy do not follow the general rules observed in the s- and p-blocks. These anomalies are due to factors like additional electron shielding, orbital contraction, and complex electron configurations that affect chemical properties differently than in the main-group elements.

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