Answer the following:
1. How could the modern periodic table remove various anomalies of Mendeleev’s periodic table?
2. In the modern periodic table, which are the metals, non-metals and metalloids among the first twenty elements?
3. What are the demerits of Mendeleev’s periodic table?
4. Define atomic size. How does it vary in a period and in a group?
Mendeleev predicted the existence of certain elements not known at that time and named two of them as eka-aluminium, and eka-silicon.
(a) Name the element which has taken the place of (i) eka-aluminium and (ii) eka-silicon
(b) Mention the period/periods of these elements in the modern periodic table.
(c) Write the group/groups of these elements in the modern periodic table.
(d) Classify these elements as metals, non-metals or metalloids.
(e) How many valence electrons are present in the atoms of each of these elements?