- How do we classify elements?
- What were the two criteria used by Mendeleev’s creating his periodic table?
- Why did Mendeleev leave some gaps in his Periodic Table?
- In Mendeleev’s Periodic Table, why was there no mention of noble gases like helium, neon and argon?
- Would you place the two isotopes of chlorine, C1-3S and Cl-37 in different slots because of their different atomic masses or in the same slot because of their chemical properties being same? Justify your answer.
-
We classify elements according to their properties and increasing atomic numbers so that we may obtain elements in regular order of their properties.
-
Atomic mass of the elements and similarity in physical and chemical properties of an element are the two criteria used by Mendeleev’s in creating his periodic table.
-
Mendeleev’s leave some gap in his periodic table because he believed that certain more elements existed but were not discovered till that lime.
-
Noble gases like helium, neon and argon were not discovered till that time.
-
Isotopes of chlorine, Cl-35 and Cl-37 have same atomic number and electronic configuration. So according to Modern periodic table we place them in same slot. Also due to same chemical properties of Cl-35 and Cl-37 they are placed in same slot.