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Syllabus
Periodic Table and Periodicity in Properties — Syllabus
NIOS · Class 12 · Chemistry
What Periodic Table and Periodicity in Properties covers in NIOS Class 12 Chemistry: 4 topics, for the 2026-27 session.
45 questions30 flashcards5 concepts
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4 Topics · NIOS Class 12 Chemistry · 2026-27
Topics in Periodic Table and Periodicity in Properties
1
Early Attempts at Classification of Elements
- Dobereiner's Triads (1817): Elements grouped in sets of three where the atomic weight of the middle element is approximately the arithmetic mean of the other two. Example: Li (6.94), Na (22.99), K (39
- Limitation of Dobereiner's Triads: Could only classify a few elements; insufficient data on atomic weights at that time.
- Newlands' Law of Octaves (1863): Elements arranged in increasing order of atomic weights; every eighth element had similar properties to the first — like musical octaves (sa, re, ga...). Example: Li a
2
Mendeleev's Periodic Table
- Mendeleev (1869) arranged elements in increasing order of atomic weights and grouped elements with similar chemical properties in the same vertical column (group).
- Mendeleev's Periodic Law: 'The properties of elements are periodic functions of their atomic weights.'
- Mendeleev's table had 8 groups (I to VIII) and several periods.
3
Modern Periodic Law and Long Form of the Periodic Table
- Moseley (1913) discovered that atomic number (number of protons) is the fundamental property of an element, not atomic weight. He changed the basis of the periodic table.
- Modern Periodic Law: 'The properties of elements are periodic functions of their atomic numbers.'
- This solved all the defects of Mendeleev's table — isotopes got the same place (same atomic number), and anomalous pairs like Co-Ni were correctly arranged.
4
IUPAC Nomenclature for Elements with Atomic Number > 100
- For elements with atomic number greater than 100 (and specifically used for > 103), IUPAC (1994/1997) developed a systematic naming system to avoid naming disputes.
- Numerical roots used: 0=nil, 1=un, 2=bi, 3=tri, 4=quad, 5=pent, 6=hex, 7=sept, 8=oct, 9=enn.
- Rule: Write the roots for each digit of the atomic number in order, then add 'ium' at the end.
Key Concepts
Dobereiner discovered that certain elements couldJohn Newlands arranged elements in orderDmitri Mendeleev arranged elements by increasingIn 1913The modern periodic table perfectly matches
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What are the important topics in Periodic Table and Periodicity in Properties for NIOS Class 12 Chemistry?
Key topics in Periodic Table and Periodicity in Properties include Early Attempts at Classification of Elements, Mendeleev's Periodic Table, Modern Periodic Law and Long Form of the Periodic Table, IUPAC Nomenclature for Elements with Atomic Number > 100. Study these first, then practise questions on each for the NIOS Class 12 board exam.
How should I revise Periodic Table and Periodicity in Properties for the NIOS Class 12 board exam?
Learn the core ideas first, then work through the 45 practice questions on Periodic Table and Periodicity in Properties. Revise definitions regularly and use flashcards for quick recall before the exam.
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