Category: Ch 5 – Periodic Classification of Elements

Hess’s law states that the standard reaction enthalpy for overall reaction taking place in several steps will be equal to the sum of standard enthalpies of intermediate reaction steps by assuming that each step occurs at the same temperature.

Trends in Modern Periodic Table In a group – Elements have the same number of valence electrons. Down the group – number of shells increases. In a period – Elements have the same number of shells. Along the period – valence shell electrons increase by one unit. Variation of Valency Valency of an element can…

The modern periodic table is also classified into metals, non-metals and metalloids. Metals Metals are electropositive as they form bonds by losing electrons. In general cases, oxides of metals are basic in nature. Examples: Includes iron, copper, silver, mercury, lead, aluminum, gold, platinum, zinc, nickel and tin. Non-metals Nonmetals are electronegative as they form bonds…

The modern periodic table contains 18 vertical columns known as groups. Group 1 elements are known as alkali metals.Group 2 elements are known as alkaline earth metals.Group 15 elements are known as pnicogens.Group 16 elements are known as chalcogens.Group 17 elements are known as halogens.Group 18  elements are known as noble gases. Alkali Metals The…

Elements present in the same period have the same number of shells which is equal to the period number. A period is a row of the periodic table that is horizontal. The periodic table contains seven periods, each of which starts at the left. On moving from left to right in a given period, the number of…

In the past, scientists believed that an element’s qualities were periodic functions of its atomic mass. Mendeleev arranged 63 elements in a vertical column named groups and horizontal rows called periods based on this idea. This approach was disregarded since it was unable to account for the locations of several elements, rare earth metals, and…

The physical and chemical characteristics of elements are a periodic function of their atomic masses, in accordance with Mendeleev’s Periodic Law. Mendeleev organised the elements in ascending order of their atomic masses after classifying them according to their atomic masses. The physical and chemical properties of elements are periodic functions of their atomic weights. Features…

Dobereiner’s Triads Dobereiner arranged a group of three elements with similar properties in the order of increasing atomic masses and called it a triad. He showed that the atomic mass of the middle element is approximately the arithmetic mean of the other two. But, Dobereiner could identify only the following three triads from the elements known at that time.…

Periodic element classification is the process of categorizing the elements into various classes. This strategy involves grouping like things together and separating those that are unrelated by comparing the characteristics of several elements. It aids in our comprehension of how various compounds combine to form various elements. Without the classification of elements, it would be…