Lecture Notes: The Periodic Table and Periodic Law

Introduction to the Periodic Table

• Dimitri Mendeleev: Initially organized the periodic table by recurring properties of elements.
• Revision into Periodic Law: Properties are periodic functions of atomic numbers rather than atomic masses.
• Modern Table: Elements arranged by increasing atomic number.

Periodic Law

• Definition: Recurring properties of elements correspond to their atomic numbers.
• Modern Arrangement: Elements are organized by atomic number to reflect periodic law.

Structure of the Modern Periodic Table

• Each Box: Represents an element.
• Periods: Rows in the table.
  • Display periodicity of properties.
  • Start of each new row signifies a repetition of shared properties.
• Groups: Columns in the table.
  • Elements in the same column display similar behaviors.
• Total: 7 periods and 18 groups.

Historical Notation

• Old Group Numbering: Used Roman numerals (I-VIII) and skipped the middle section.
• Current Notation: Uses numerical symbols for clarity.

Special Sections

• Lanthanides and Actinides: Removed from the main body to save space; placed below the rest.

Types of Elements

• Categories: Metals, metalloids, non-metals.
• Behavior: Different types exhibit distinct properties, to be discussed further.

Importance in Chemistry

• Utility: The periodic table is frequently referenced to describe atoms and predict chemical behavior.

These notes summarize the organization and significance of the periodic table in understanding and predicting chemical properties and behaviors.