What are the features and merits of the long form of the periodic table ?



Features of the long form periodic table

The general features of the Long Form Periodic Table (IUPAC 1984) are;

(i) The long form periodic table (IUPAC 1984) consists of 18 vertical columns and 18 groups. These groups are numbered 1 to 18 from the left, using Arabic numerals.

(ii) Elements of the groups 1 and 2 , and groups 13 to 17 are called main group elements. These are also called typical or representative or normal elements.

(iii) The elements of the groups 3 to 12 in the middle of the periodic table are called transition elements.

(iv) Elements with atomic numbers 58 to 71(Ce to Lu) occurring after lanthanum are called lanthanides.

(v) Elements with atomic numbers 90 to 103(Th to Lr) are called actinides.

(vi) Both these series of elements (lanthanides and actinides), are placed in mass separate box atomic the bottom of the periodic table. This is done to avoid excessive width of the periodic table.

(vii) There are seven (7) horizontal rows in this periodic table called periods. Thus, there are seven periods in this periodic table.

(a) First period contains 2 element, and is called shortest period.

(b) Second and third periods contains 8 elements each, and are called Short periods.

(c) Fourth and fifth periods contain 18 elements each, and are called long periods.

(d) Sixth period contains 32 elements, and is called Longest Period.

(e) Seventh period is incomplete, and is called Incomplete period.

(f) Each period begins with the element that has been one electron in mass new main shell.

(g) The elements belonging to the group 1 and are collectively called alakali metals.

(h) The elements belonging to the group 2 are collectively called alkaline earth metals.

(i) The elements belonging to the group 17 are collectively called halogens.

(j) The elements belonging to the group 18 are collectively called noble gas elements.

(k) Metals are located in the left and the central parts of the periodic table. Nometals are located in the upper right portion of the periodic table.

Merits of the long form periodic table

The long form periodic table has been the following merits:

(i) Long form periodic table is based upon the atomic numbers which is more fundamental properties of the atom.

(ii) It relates the position of an element in the periodic table with its electronic configuration.

(iii) It removes all the anomalies and drawbacks of the Mendeleef’s table.

(iv) It shows changes in the properties of various elements while moving across mass period or down mass group more clearly.