Class 10 Science - MAHARASHTRA
Periodic Classification of Elements
The chapter 'Periodic Classification of Elements' in Class 10 Maharashtra State Board (MSBSHSE) science explores how scientists organized chemical elements into a systematic table. It covers historical attempts like Dobereiner's Triads and Newlands' Law of Octaves, Mendeleev's Periodic Table, and finally, the Modern Periodic Table proposed by Henry Moseley. You will learn about periodicity, electronic configurations, and how various physical and chemical properties such as valency, atomic size, metallic and non-metallic character vary across periods and groups. This is a high-scoring chapter crucial for understanding chemical bonding.
Start Learning FreeKey Concepts
Dobereiner's Triads
Groups of three elements with similar properties where the atomic mass of the middle element is approximately the mean of the other two.
Newlands' Law of Octaves
When elements are arranged in increasing order of atomic mass, every eighth element has properties similar to the first, much like musical notes.
Mendeleev's Periodic Table
States that properties of elements are a periodic function of their atomic masses, leaving gaps for undiscovered elements.
Modern Periodic Law
States that properties of elements are a periodic function of their atomic numbers, resolving many anomalies of Mendeleev's table.
Valency
The combining capacity of an element, determined by the number of valence electrons in its outermost shell.
Atomic Radius
The distance between the center of the nucleus and the outermost shell of an isolated atom, measured in picometres (pm).
Important Formulas
Board Exam Info
In the Maharashtra (MSBSHSE) Class 10 Science Part 1 board exam, this chapter typically carries around 3 to 4 marks without options, and up to 6 marks with options. Common question types include identifying trends in periods and groups, giving scientific reasons for anomalies, writing merits and demerits of earlier classifications, and answering sub-questions based on given table extracts.
Frequently Asked Questions
Why was Mendeleev's periodic table modified into the Modern Periodic Table?
Mendeleev arranged elements by atomic mass, which led to anomalies like incorrect order for some heavier elements and isotopes having no fixed place. Moseley discovered atomic number is a more fundamental property, leading to the Modern Periodic Table.
How does metallic character change down a group and across a period?
Metallic character increases down a group because atomic size increases, making it easier to lose electrons. It decreases across a period from left to right as the nuclear charge increases, making it harder to lose electrons.
What is the difference between periods and groups in the Modern Periodic Table?
Periods are the horizontal rows (1 to 7) representing the total number of electron shells, while groups are the vertical columns (1 to 18) representing elements with the same number of valence electrons and similar chemical properties.
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