Periodic Table Organization and Classification

Periodic Table Organization and Classification

• Periodic law: Chemical and physical properties repeat periodically as atomic number increases.
• Groups (families): Vertical columns; elements have similar properties.
• Periods: Horizontal rows; elements' properties change gradually.
• Representative elements: Groups 1, 2, and 13-18; diverse properties.
• Transition metals: Groups 3-12; often good conductors.
• Metals: Shiny, solid at room temp, good conductors of heat/electricity.
• Alkali metals: Group 1 (except H); highly reactive.
• Alkaline earth metals: Group 2; also reactive.
• Transition and inner transition metals: Subsections within the transition metals.
• Lanthanide and Actinide series: Inner transition metals (bottom rows).
• Nonmetals: Gases or brittle solids, poor conductors.
• Halogens: Group 17; highly reactive.
• Noble gases: Group 18; extremely unreactive.
• Metalloids: Properties of both metals and nonmetals.

Historical Development of the Periodic Table

• Lavoisier: Compiled a list of known elements in the late 1700's.
• New discoveries in the 1800s spurred the need for organization.
• Newlands: Arranged elements by atomic mass, noticed 8 element pattern.
• Mendeleev: Created an early periodic table, organized by atomic mass and properties; predicted undiscovered elements.
• Moseley: Refined Mendeleev's table, arranging elements by atomic number; resulted in a clear, periodic pattern.

Modern Periodic Table

• Contains Name, Symbol, Atomic Number, and Atomic Mass for each element.
• Columns are called groups or families.
• Rows are called periods.

Element Classification

• Elements are broadly classified as metals, nonmetals, and metalloids.

Electron Configuration and Periodic Table Structure

• Electron configurations determine chemical properties.
• Valence electrons: Electrons in the outermost energy level. Relates to element position on PT.
• Group 1: 1 valence electron
• Group 2: 2 valence electrons
• Groups 13-18: Valence electrons = group number - 10
• Energy levels of valence electrons correspond to the period of the element.
• Blocks (s, p, d, f) correspond to filled/partially filled energy sublevels.
• S-block: Groups 1 & 2 (plus He).
• P-block: Groups 13-18
• D-block: Transition metals (largest block). They have filled outermost s orbitals & filled/partially filled d orbitals.
• F-block: Inner transition metals (lanthanides & actinides). Filled outermost s orbitals & filled/partially filled 4f or 5f orbitals.

Periodic Trends: Atomic Size

• Atomic radius decreases left-to-right across a period.
• Atomic radius increases down a group.
• Metallic atomic radius = half distance between adjacent atoms in a crystal lattice.

Periodic Trends: Ionization Energy and Electronegativity

• Ionization energy: Energy to remove an electron. Increases left-to-right, decreases down a group.
• First ionization energy: Energy to remove the first electron.
• Successive ionization energies: Increasing by each removal.
• Octet rule: Atoms tend to gain/lose/share electrons to achieve 8 valence electrons (exceptions occur).
• Electronegativity: Ability of an atom to attract electrons in a bond. Increases left-to-right, decreases down a group.

Test your knowledge on the organization and classification of the periodic table. This quiz covers periodic law, groups, periods, and the various classes of elements including metals, nonmetals, and metalloids. Understand the characteristics of different groups and their historical development.