Periodic Classification of Elements

Class 10 Science • Chapter 1

Chapter Overview

This chapter explains how elements were classified, the development of the modern periodic table and the relationship between an element's position and its chemical properties.

📘 Notes

Complete chapter notes covering concepts, periodic trends and important definitions.

❓ Important Questions

Exam-focused, reasoning and competency-based practice questions.

📝 Previous Year Questions

Official CBSE previous-paper resources and chapter-focused practice.

Topics Covered

Early Classification of Elements

Döbereiner's Triads

Newlands' Law of Octaves

Mendeleev's Periodic Table

Modern Periodic Law

Modern Periodic Table

Groups and Periods

Electronic Configuration

Valency

Atomic Size

Metallic Character

Non-Metallic Character

Periodic Trends

Reactivity and Position

Quick Revision

Döbereiner → Triads
Newlands → Law of Octaves
Mendeleev → Periodic Table
Modern Periodic Law → Atomic Number
Vertical columns → Groups
Horizontal rows → Periods
Atomic size generally decreases across a period
Atomic size generally increases down a group

Official Study Resources

CBSE Academic – Curriculum 2026-27 → NCERT – Official Textbooks →