1. What are the limitations of Dobereiner's classification of elements?
2. What are the limitations of Newland's law of octaves?
3. What we're the criteria used by Mendeleev in creating his periodic table?
4. State the merits of Mendeleev's classification of elements.
5. Why could no fixed position be given to hydrogen in Mendeleev's periodic table?
6. State the differences between Mendeleev's and Modern periodic table.
Answers
Answer:
octaves?
3. What we're the criteria used by Mendeleev in creating his periodic table?
4. State the merits of Mendeleev's classification of elements.
5. Why could no fixed position be given to hydrogen in Mendeleev's periodic table?
6. State the differences between Mendeleev's and Modern periodic table.
Answer:
1.Dobereiner could find only three triads; . i.e total of 9 elements only. However the total number of elements were more than that of those encompassed in Dobereiner's Triad.
2.Newland's law of octaves held true only for elements up to calcium. Elements with greater atomic masses could not be accommodated into octaves. The elements that were discovered later could not be fit into the octave pattern.
3.The criteria used by Mendeleev in creating his periodic table were: (i) The atomic mass of the elements was used to arrange the elements. (ii) Grouping the elements according to their similar chemical properties.
4. Mendeleev's periodic law predicted the existence of certain elements such as gallium, scandium and germanium, which were not discovered at that time. 2. Mendeleev's periodic table could also predict the properties of various elements based on their position in the periodic table.
5.Hydrogen had no fixed position in Mendeleev's Periodic table because it resembles alkali metal by forming positive ions and resembles halogens by forming diatomic molecule.
6.Mendeleev's periodic table
-Mendeleev's periodic table is based on atomic mass
Modern periodic table -The modern periodic table is based on the atomic number