Introducción a la Tabla Periódica

Introduction to the Periodic Table

• The periodic table is a tabular arrangement of all known chemical elements.
• Elements are organized by their atomic number (number of protons), electron configuration, and recurring chemical properties.
• The table is arranged in rows (periods) and columns (groups or families).
• Elements in the same group share similar chemical properties.

Organization of the Periodic Table

• Periods: Horizontal rows, showing increasing atomic number. Elements in the same period have different properties; properties gradually change across the period.
• Groups (Families): Vertical columns, often characterized by similar valence electron configurations, leading to similar chemical properties. Elements in the same group tend to have similar reactivity and bonding behavior.

Elements' Classification

• Metals: Located on the left and center of the table. Properties include: high electrical and thermal conductivity, malleability (can be hammered into sheets), ductility (can be drawn into wires), and generally shiny surfaces.
• Nonmetals: Located on the right side of the table. Properties include: poor conductors of heat and electricity, brittle in solid form, and often have varied appearances.
• Metalloids (Semi-metals): Located along the staircase line separating metals and nonmetals. These elements exhibit properties intermediate between metals and nonmetals, which can vary with conditions.

Key Element Groups

• Group 1 (Alkali Metals): Highly reactive metals that readily form ions with a +1 charge.
• Group 2 (Alkaline Earth Metals): Reactive metals, less reactive than Group 1, forming +2 ions.
• Group 17 (Halogens): Highly reactive nonmetals that readily form -1 ions, forming salts with metals.
• Group 18 (Noble Gases): Inert gases with very low reactivity due to their complete valence electron shells.

Atomic Structure and the Periodic Table

• Atomic number: The number of protons in an atom's nucleus; it defines the element's position in the table.
• Atomic mass: The average mass of an element's isotopes, reflecting the abundance of each isotope.
• Valence electrons: Electrons in the outermost electron shell that determine chemical bonding and properties.

Periodic Trends

• Atomic radius: Tends to increase down a group and decrease across a period.
• Ionization energy: The energy required to remove an electron from an atom; ionization energy generally increases across a period and decreases down a group.
• Electronegativity: The ability of an atom to attract electrons in a chemical bond; electronegativity generally increases across a period and decreases down a group.

Important Concepts

• Periodicity: The trend of repeating properties among elements in the periodic table, correlated with electron configurations.
• Isotopes: Atoms of the same element with different numbers of neutrons, leading to varied atomic masses.
• Ions: Atoms that have lost or gained electrons, resulting in a positive or negative charge, respectively.

Common Elements and Their Uses

• Examples of common elements and their uses (e.g., iron in construction, carbon in materials) will be discussed in class.