Question

Salient features of the long term periodic table from left to right.

Answer 1

The long form of periodic table is arranged in increasing order of their atomic numbers. The prediction of properties, elements and their compounds can be made with precision.

Complete answer:
The salient features of the Modern periodic table from left to right are given below:
The periodic table has 18 vertical columns which are called groups. and seven horizontal rows which are called periods.
The elements of group 1,2, 13, 14, 15, 16 and 17 are known as the main group or representative elements.
The elements of group 3,4,5,6,7,8,9, 10 ,11 and 12 are known as transition elements
Element 18 are called noble gases or inert gases.
The first period contains only 2 elements and is the shortest period.
The second (Lithium to Neon) and third period (Sodium to Argon) contain 8 elements – Hydrogen and Helium and are called short periods.
The fourth (Potassium to Krypton) and fifth period (Rubidium to Xenon) contains 18 elements. These are long periods.
The sixth period (Cesium to Radon) contains 32 elements and it is the longest period.
The seventh period is an incomplete period.
In group 3 of the sixth period there is a set of elements with atomic number 57 to 71. They are known as lanthanides.
In group 3 of seventh period the elements with atomic number 89 – 103 are known as actinides.
In the periodic table Lanthanides and Actinides are shown in the bottom of the periodic table.

Note: In the particular group electrons in the outermost orbit remain the same and the properties of the element depend on the number of electrons in their outermost shell. Thus, periodicity plays an important feature in modern periodic tables.