Tabla Periódica de Elementos

Introduction

• The periodic table is a tabular arrangement of chemical elements, organized by atomic number, electron configuration, and recurring chemical properties.
• Its structure reveals patterns in element behavior and allows predictions about undiscovered elements.
• The table is a fundamental tool in chemistry, physics, and other sciences.

Organization of the Periodic Table

• Elements are arranged in rows (periods) and columns (groups or families).
• Period numbers correspond to the highest principal quantum number of the outermost electrons in atoms of elements within that period.
• Elements in the same group share similar chemical properties due to having the same number of valence electrons.
• Groups are often labeled with Roman numerals and letters (e.g., IA, IIA, VIIA, etc.).

Classification of Elements

• Elements are categorized as metals, nonmetals, and metalloids based on their properties.
• Metals generally conduct heat and electricity, possess a high luster, and are malleable.
• Nonmetals typically are poor conductors and often brittle.
• Metalloids exhibit properties intermediate between metals and nonmetals; they can be both conductors and insulators under certain conditions.

Atomic Number and Atomic Mass

• An element's atomic number represents the number of protons in its nucleus; it uniquely identifies each element.
• Atomic mass is the average mass of an element's naturally occurring isotopes, weighted by their abundance.
• Atomic masses are typically displayed in atomic mass units (amu).

Trends in Periodic Properties

• Atomic radius generally decreases across a period and increases down a group.
• Ionization energy generally increases across a period and decreases down a group.
• Electronegativity generally increases across a period and decreases down a group.
• Metallic character generally decreases across a period and increases down a group..

Importance of the Periodic Table

• Predicting properties of yet-undiscovered elements is possible.
• Understanding relationships between elements and compounds.
• Classifying and organizing known chemical elements.
• The periodic table serves as a fundamental tool in chemistry.

Key Groups and Their Properties

• Group 1 (Alkali Metals): Highly reactive metals.
• Group 2 (Alkaline Earth Metals): Reactive metals, less reactive than alkali metals.
• Group 17 (Halogens): Highly reactive nonmetals.
• Group 18 (Noble Gases): Unreactive gases.
• Transition Metals: Elements with variable properties in different oxidation states; located in the d-block of the table.

History of the Periodic Table

• Dmitri Mendeleev is credited with creating the first widely accepted periodic table.
• He organized elements by increasing atomic mass, noting recurring patterns.
• Subsequent developments refined the table, particularly with the knowledge of atomic structure.

Modern Periodic Table

• The current periodic table is based primarily on atomic number, not atomic mass.
• This modification corrects inaccuracies of earlier versions.
• Modern periodic trends and predicted properties can be derived directly from the table.