Structure of the Modern Periodic Table

The modern periodic table is a tabular arrangement of elements based on their atomic numbers, highlighting periodic trends in their properties.

Features of the Modern Periodic Table:

• 18 vertical columns (called groups) arranged from left to right.
• 7 horizontal rows (called periods).
• Each box in the table represents an element, with its atomic number indicated at the top.
• The table contains a total of 118 elements, including the lanthanide and actinide series.

Classification of Elements:

• Main group elements: Groups 1, 2, 13-17.
• Transition elements: Groups 3-12.
• Noble gases (inert gases): Group 18 (outermost shell completely filled, making them non-reactive).

Periodic Trends:

• The number of shells in an atom determines its period number.
• Period 1 contains only 2 elements (the shortest period).
• Periods 2 and 3 contain 8 elements each (short periods).
• Periods 4 and 5 contain 18 elements each (long periods).
• Period 6 (Group 3) contains lanthanides (rare earth elements).
• Period 7 (Group 3) contains actinides (radioactive elements).

The modern periodic table is divided into four blocks:

• s-block: Groups 1 and 2.
• p-block: Groups 13 to 18.
• d-block: Groups 3 to 12 (transition elements).
• f-block: Lanthanide and Actinide series (placed separately at the bottom).

Metals, Nonmetals, and Metalloids:

• A zigzag line in the p-block separates metals, nonmetals, and metalloids.
• Metalloids lie along the border of this zigzag line.
• Metals are positioned to the left of the line.
• Nonmetals are positioned to the right of the line.