Page 1: Structure and Organization of the Periodic Table

The modern tavola periodica evolved from Mendeleev's 1869 arrangement of 63 elements to today's comprehensive system of 118 elements. The table's organization follows specific principles based on atomic structure and electronic configuration.

Definition: The atomic number (Z) indicates the number of protons in an atom's nucleus and determines an element's position in the periodic table.

Highlight: The periodic table is organized into:

• Periods (rows): Indicate the main electron shell
• Groups (columns): Show the number of valence electrons

Example: The table is divided into three main categories:

1. Metals (left side)
2. Non-metals (upper right)
3. Metalloids (diagonal border region)

Vocabulary:

• Valence electrons: Outer shell electrons that participate in chemical bonding
• IUPAC: International Union of Pure and Applied Chemistry
• Lewis symbols: Representation showing valence electrons as dots around element symbols

Quote: "La periodicità degli elementi è dovuta a come sono disposti loro elettroni più esterni intorno al nucleo elettroni detti di valenza"

The table features eight main groups, with elements sharing similar chemical properties within each group. Metalli occupy the left side and include alkali metals and alkaline earth metals, while non metalli are found on the right side, including halogens and noble gases. Semimetalli form a diagonal boundary between metals and non-metals, exhibiting intermediate properties.