or

Differentiate between.

  1. Mendeleev's and the modern periodic table
  2. Periods and groups
  3. s-block and p-block elements
  4. Alkali metals and halogens
  5. Alkali metals and alkaline earth metals
  6. Duplet stable and octet stable

a. Mendeleev's and the modern periodic table.

Mendeleev'sModern
It supported the first scientific study of elements.It is the latest and standard table of elements.
Elements were arranged with the increasing order of their atomic weight.Elements were arranged with the increasing order of their atomic number.
It had several gaps for undiscovered elements.Most of the elements are discovered and arranged.
It was unable to arrange isotopes.It is able to arrange isotopes.
It didn't have lanthanides and actinides series.It consists of lanthanides and actinides series.

b. Periods and groups.

PeriodsGroups
The horizontal rows in the periodic table are periods of the periodic table.The vertical column in the periodic table are groups of the periodic table.
The change in valency is found in a period.The valency of elements remains the same in a group.
A period contains the elements of different blocks.A group contains the element of the same block.

c. s-block elements and p-block elements.

s-blockp-block
The last electron of these elements enters the s-orbital of the outermost shell.The last electron of these elements enters the p-orbital of the outermost shell.
These elements are alkali metals.These elements are non-metals.
These elements are electronically positive. i.e. they have positive valency.These elements have negative valency.

d. Alkali metals and halogens.

Alkali metalsHalogens
These elements are highly reactive electro-positive metals.These elements are highly reactive electro-negative metals.
These elements are good conductors of electricity.These elements are insulators of electricty.
These elements have positive valency.These elements have negative valency.

e. Alkali metals and alkaline earth metals.

Alkali metalsAlkaline earth metals
These elements are placed in group IA of the periodic table.These elements are placed in group IIA of the periodic table.
These elements are more reactive.These elements are comparatively less reactive.
These elements have valency +1.These elements have valency +2.

f. Duplet stable state and octet stable state.

Duplet stableOctet stable
The atom which has a stable electronic configuration having 2 electrons in its valance shell is duplet stable.The atom which has a stable electronic configuration having 8 electrons in its valance shell is octet stable.
This is possible only in 1st or 2nd shell.This is possible in any shell of an atom.