Periodic Classification of Elements
Problem 1: Did Dobereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.solution: Only one triad of Dobereiner’s triads exist in the columns of Newlands’ octaves. The triad formed by the elements Li, Na, and K of Dobereiner’s triads also occurred in the columns of Newlands’ octaves. Dobereiner’s triads CaClNaSr BrK BaI Newlands’ octaves Li Be B C N OF Na Mg Al Si P SCl K Ca Cr TiMnFeCo and Ni CuZn Y InAs SeBr RbSr Ce and LaZr− −
Problem 2: What were the limitations of Dobereiner’s classification? solution: Limitation of Dobereiner’s classification: All known elements could not be classified into groups of triads on the basis of their properties.
Problem 3: What were the limitations of Newlands’ Law of Octaves? solution: Limitations of Newlands’ law of octaves:(i) It was not applicable throughout the arrangements. It was applicable up to calcium only. The properties of the elements listed after calcium showed no resemblance to the properties of the elements above them. (ii) Those elements that were discovered after Newlands’ octaves did not follow the law of octaves. (iii) The position of cobalt and nickel in the group of the elements (F, Cl) of different properties could not be explained. (iv) Placing of iron far away from cobalt and nickel, which have similar properties as iron, could also not be explained.
Problem 4: Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements: K, C, Al, Si, Ba?
{written by=ARUN KUMAR}
Problem 1: Did Dobereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.solution: Only one triad of Dobereiner’s triads exist in the columns of Newlands’ octaves. The triad formed by the elements Li, Na, and K of Dobereiner’s triads also occurred in the columns of Newlands’ octaves. Dobereiner’s triads CaClNaSr BrK BaI Newlands’ octaves Li Be B C N OF Na Mg Al Si P SCl K Ca Cr TiMnFeCo and Ni CuZn Y InAs SeBr RbSr Ce and LaZr− −
Problem 2: What were the limitations of Dobereiner’s classification? solution: Limitation of Dobereiner’s classification: All known elements could not be classified into groups of triads on the basis of their properties.
Problem 3: What were the limitations of Newlands’ Law of Octaves? solution: Limitations of Newlands’ law of octaves:(i) It was not applicable throughout the arrangements. It was applicable up to calcium only. The properties of the elements listed after calcium showed no resemblance to the properties of the elements above them. (ii) Those elements that were discovered after Newlands’ octaves did not follow the law of octaves. (iii) The position of cobalt and nickel in the group of the elements (F, Cl) of different properties could not be explained. (iv) Placing of iron far away from cobalt and nickel, which have similar properties as iron, could also not be explained.
Problem 4: Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements: K, C, Al, Si, Ba?
Problem 2: What were the limitations of Dobereiner’s classification? solution: Limitation of Dobereiner’s classification: All known elements could not be classified into groups of triads on the basis of their properties.
Problem 3: What were the limitations of Newlands’ Law of Octaves? solution: Limitations of Newlands’ law of octaves:(i) It was not applicable throughout the arrangements. It was applicable up to calcium only. The properties of the elements listed after calcium showed no resemblance to the properties of the elements above them. (ii) Those elements that were discovered after Newlands’ octaves did not follow the law of octaves. (iii) The position of cobalt and nickel in the group of the elements (F, Cl) of different properties could not be explained. (iv) Placing of iron far away from cobalt and nickel, which have similar properties as iron, could also not be explained.
Problem 4: Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements: K, C, Al, Si, Ba?
{written by=ARUN KUMAR}
With the help of ncert solution on LM
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