9. Classification of Elements- The Periodic Table
1. The atomic weight of the middle element is the average of the atomic weights of the first and third elements. This statement is called the _____________________.
2. __________ was the first to assign atomic numbers to the elements.
3. Mendeleef arranged the elements known at that time in a chart in a systematic order in the increasing order of their ______________.
4. Mendeleef divided the chart into 8 vertical columns known as ________.
5. Mandeleeff periodic table based on _________.
6. There are eight vertical columns in Mendeleef’s periodic table called as _________.
7. Groups are represented by Roman numerals I to ______.
8. The horizontal rows in Mendeleef’s periodic table are called _________.
9. There are seven periods in the table, which are denoted by Arabic numerals 1 to _______.
10. Eka is a Sanskrit word for _________.
11. In his honour of Mendeleeff the 101th element was named as ____________.
12. ____________ found that each element emits a characteristic pattern of X-rays when subjected to bombardment by high energy electrons.
13. The number of positive charges (protons) in the atom of an element is called the ___________ of the element.
14. Moseley realized that the __________ is more fundamental characteristic of an element than its atomic weight.
15. The periodic law is changed from atomic weight concept to atomic number concept and now it is called the ______________.
16. The modern periodic table has eighteen vertical columns known as groups and seven horizontal rows known as _________.
17. The elements with similar outer shell (valence shell) electronic configurations in their atoms are in the same column called ________.
18. Elements listed in a group down to it are in the order of their increasing _________________.
19. The group of elements is also called _________ or chemical family.
20. Group1 (IA) elements are ______________.
21. Group2 (IIA) elements are ______________________.
22. Group 13 (IIIA) elements are Boron _________.
23. Group 14 (IVA) elements are _____________.
24. Group 15 (VA) elements are _____________.
25. Group 16 (VIA) elements are ___________ or (Chalcogen family).
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