1. The number of elements in Mendeleev’s periodic table is ........ elements. 2. The scientist who left empty cells in his table to be filled with discovered elements in future is... 1. The number of elements in Mendeleev’s periodic table is ........ elements. 2. The scientist who left empty cells in his table to be filled with discovered elements in future is ........ 3. Mendeleev classified the elements of each main group into ...... subgroups. 4. The nucleus of the atom contains ........ 5. The scientist who discovered that the nucleus of the atom contains positively charged protons is ........ 6. The scientist ........ discovered the main energy levels of the atom. 7. The number of energy levels in the heaviest known atom reaches ........ levels till now. 8. The number of known elements in the modern periodic table till now is ........ 9. The number of elements which exist in nature is ........ according to modern periodic table. 10. The modern periodic table consists of ........ horizontal periods. 11. The modern periodic table consists of ........ vertical groups. 12. The modern periodic table consists of ........ main blocks. 13. The elements which occupy the middle block (d) in the periodic table are called ........ 14. The transition elements start to appear from the beginning of the ........ period.
Understand the Problem
The question set focuses on various historical and scientific aspects of the periodic table and atomic structure, covering key figures and concepts in chemistry.
Answer
1. 67 elements 2. Mendeleev 3. 2 subgroups 4. positive protons 5. Rutherford 6. Bohr 7. 7 levels 8. 118 9. 92 10. 7 periods 11. 18 groups 12. 4 main blocks 13. transition elements 14. fourth period
- 67 elements 2. Mendeleev 3. 2 subgroups 4. positive protons 5. Rutherford 6. Bohr 7. 7 levels 8. 118 9. 92 10. 7 periods 11. 18 groups 12. 4 main blocks 13. transition elements 14. fourth period
Answer for screen readers
- 67 elements 2. Mendeleev 3. 2 subgroups 4. positive protons 5. Rutherford 6. Bohr 7. 7 levels 8. 118 9. 92 10. 7 periods 11. 18 groups 12. 4 main blocks 13. transition elements 14. fourth period
More Information
Mendeleev's periodic table originally had 67 elements, and he left gaps for elements he predicted would be discovered. The modern periodic table now has 118 known elements.
Tips
A common mistake is confusing the number of elements in Mendeleev's original table with the modern periodic table.
Sources
- The number of elements in Mendeleev's periodic table is - Gauthmath - gauthmath.com
- Development of the periodic table - The Royal Society of Chemistry - rsc.org
- Periodic table - Wikipedia - en.wikipedia.org
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