The Modern Periodic Table is one of the most powerful tools in chemistry. It organizes all 118 known elements in a logical way, helping us understand their properties and predict their behavior . For students from Class 8 to Class 10, mastering the periodic table is essential for excelling in science.
At Dhingra Classes Nashik, we emphasize concept-based learning to help students understand this important topic with confidence.
📘 What is the Modern Periodic Table?
The Modern Periodic Table arranges elements in the increasing order of their atomic numbers (number of protons) . This arrangement is based on the Modern Periodic Law, which states that the physical and chemical properties of elements are periodic functions of their atomic numbers .
Mendeleev’s Periodic Table vs. Modern Periodic Table
Key Improvement: Henry Moseley’s 1913 X-ray work showed that atomic number (not atomic mass) was the fundamental property that determined an element’s position, resolving inconsistencies in Mendeleev’s table .
🗂️ Structure of the Modern Periodic Table
The Modern Periodic Table consists of 7 horizontal rows called Periods and 18 vertical columns called Groups .
Periods (Horizontal Rows)
Each period corresponds to the number of electron shells in an atom .
| Period | Number of Elements | Type |
|---|---|---|
| 1 | 2 (H, He) | Shortest period |
| 2 & 3 | 8 each | Short periods |
| 4 & 5 | 18 each | Long periods |
| 6 | 32 | Longest period |
| 7 | 32 (incomplete) | Incomplete period |
Groups (Vertical Columns)
Elements in the same group have the same number of valence electrons and, therefore, similar chemical properties .
📊 Periodic Trends – The Key to Understanding
1. Valency
| Trend | Explanation |
|---|---|
| Across a Period | Valency increases from 1 to 4, then decreases to 0 |
| Down a Group | Valency remains the same |
Example: In Group 1, all elements have valency 1. In Period 3, valency changes from Na (1) to Ar (0).
2. Atomic Size (Atomic Radius)
Atomic radius is the distance from the nucleus to the outermost shell .
| Trend | Explanation |
|---|---|
| Across a Period | Decreases (increased nuclear charge pulls electrons inward) |
| Down a Group | Increases (new shells are added) |
Reason: As we move left to right in a period, the nuclear charge increases, pulling electrons closer. Moving down a group adds new shells, increasing size .
3. Metallic & Non-Metallic Character
| Trend | Explanation |
|---|---|
| Across a Period | Metallic character decreases; non-metallic character increases |
| Down a Group | Metallic character increases; non-metallic character decreases |
Metalloids (Si, Ge, As): Elements with intermediate properties between metals and non-metals .
4. Ionization Energy
Definition: Energy required to remove an electron from a gaseous atom .
5. Electronegativity
Definition: Tendency of an atom to attract shared electrons .
🧠 Tips to Master the Periodic Table
🌟 How Dhingra Classes Helps Students Master Chemistry
At Dhingra Classes Nashik, we make chemistry easy and engaging by:
Conceptual Teaching: Explaining the “why” behind every trend and rule.
Interactive Sessions: Using visual aids, mnemonics, and quizzes.
Regular Practice: Worksheets, group activities, and memory exercises.
Personalized Attention: Helping each student overcome their challenges.
📞 Contact Dhingra Classes Nashik
Phone: 98230 62106
Email: dhingraclassesnsk@gmail.com
Website: www.dhingraclassesnashik.com
Address: Plot No 3, XQ3G+H3M Deacon Homes, 301C, opp. Metro Zone, near Guru Govind Sing, Samarth Nagar, Dnyaneshwar Nagar, Pathardi Phata, Nashik, Maharashtra 422009
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