Question

Compare and contrast the arrangement of elements in Mendeleev's periodic Table and the Modern Periodic Table. [5 MARKS]

Answer 1

Each point: 1 Mark

$\begin{array}{cc}\text{Mendeleev's periodic table}& \text{Modern periodic table}\\ \text{1. Elements are arranged in the}& \text{Elements are arranged in the}\\ \text{increasing order of}& \text{increasing order of}\\ \text{their atomic masses.}& \text{their atomic numbers.}\\ \text{2. There are 8 Groups.}& \text{There are 18 Groups.}\\ \text{3. Each groups are subdivided into sub group 'a' and 'b'}& \text{Groups are not subdivided into sub-groups.}\\ \text{4. Groups for Noble gas were not present as noble}& \text{A separate group is meant for noble gases.}\\ \text{gases were not discovered by that time.}& \\ \text{5. There was no place for isotopes.}& \text{This problem has been rectified as slots are}\\ & \text{determined according to atomic number.}\end{array}$