How does the modern periodic table differ from Mendeleev?s table?
Dear student,
Differences between Mendeleev's Periodic table and Modern periodic table:
Mendeleev's periodic table
Modern Periodic table
1. According to Mendeleev's theory, the physical and chemical properties are the periodic function of the atomic weights of elements.
1. It considers that chemical and physical properties are the periodic function of the atomic numbers of elements.
2.The basis of classification was the formula of hydrides and oxides made by the elements.
2. The basis of classification is the electronic configuration of the elements.
4. The noble elements were not included as they were not discovered at that time.
4.It included noble elements in gr. 18 as a last and separated group.
5. It has an ambiguity in the position of some elements as, some elements with larger atomic weights are placed before elements with smaller atomic weights without any justified reason.
5. Here, all are arranged systematically with increasing atomic no. and weight too.
6. According to this theory, the isotopes with different atomic weights, should be placed in different positions, but are not given any position and no, justified reason was explained.
6. The isotopes were assigned the same position as they have the same atomic no.
7.Some different elements were grouped together while some similar elements were placed in different groups. Ex: alkali metals like Li, Na, K were placed with coinage metals Cu, Ag, Au, etc.
7. No such confusion, the coinage metals have their own position in d-block and alkali metals are placed in s-block elements
8. Group VIII has three elements together, like Fe, Co, Ni
8. These elements are placed in different groups, under d-block elements.
Regards
Differences between Mendeleev's Periodic table and Modern periodic table:
| Mendeleev's periodic table | Modern Periodic table |
| 1. According to Mendeleev's theory, the physical and chemical properties are the periodic function of the atomic weights of elements. | 1. It considers that chemical and physical properties are the periodic function of the atomic numbers of elements. |
| 2.The basis of classification was the formula of hydrides and oxides made by the elements. | 2. The basis of classification is the electronic configuration of the elements. |
| 4. The noble elements were not included as they were not discovered at that time. | 4.It included noble elements in gr. 18 as a last and separated group. |
| 5. It has an ambiguity in the position of some elements as, some elements with larger atomic weights are placed before elements with smaller atomic weights without any justified reason. | 5. Here, all are arranged systematically with increasing atomic no. and weight too. |
| 6. According to this theory, the isotopes with different atomic weights, should be placed in different positions, but are not given any position and no, justified reason was explained. | 6. The isotopes were assigned the same position as they have the same atomic no. |
| 7.Some different elements were grouped together while some similar elements were placed in different groups. Ex: alkali metals like Li, Na, K were placed with coinage metals Cu, Ag, Au, etc. | 7. No such confusion, the coinage metals have their own position in d-block and alkali metals are placed in s-block elements |
| 8. Group VIII has three elements together, like Fe, Co, Ni | 8. These elements are placed in different groups, under d-block elements. |
Regards
