Classification of elements and periodicity in properties

Classification of Elements:Our surroundings are made up of basic units known as elements. Only 31 elements were known around 1800. Later, with technological advancements, 63 more elements were discovered. As the number of elements grew, it became necessary to classify them on a regular basis. There are currently 118 elements, 93 of which are found naturally, and the rest were created in laboratories. It was difficult to study these elements independently without first establishing a relationship between them based on their properties. As a result, these elements are organised or classified into different categories or groups based on similarities and differences in their properties, as well as periodicity. Because the elements in the classification of elements are arranged in groups known as periods, this classification system is known as the periodic classification of elements. What is the Classification of Elements? The grouping of elements with similar characteristics is known as the Classification of elements. Even though each element is distinct from the others, some elements share similarities. Based on these similarities, scientists were eventually successful in grouping the various elements into groups or chemical families, so that, similar elements were grouped together and dissimilar elements were separated from one another after showing a group. Thus, the Classification of elements leads to the formation of the periodic table. Need for Classification of Elements...

Periodicity of properties of the elements The periodicity of properties of the elements is caused by the periodicity in The properties of elements in the same group of the periodic system are, although similar, not identical. The trend in properties from the lighter to the heavier elements may be attributed to changes in the strength of binding of the outer electrons and especially to the increasing size of the atoms. Other chemical and physical classifications Certain methods of classifying elements on the basis of chemical properties are not strictly related to the groups in which the elements appear. Such

Classification Of Elements And Periodicity In Properties Classification and Blocks in Periodic Table: Topics covered: Earlier classifications Dobereiner’s Triads Newland’s law of octaves Mendeleev’s Periodic Classification Modern Periodic Table or Moseley’s Periodic Law With the discovery of a large number of elements, it became difficult to study the elements individually, so the classification of elements was done to make the study easier. Earlier Classification: Dobereiner’s Triads: In triads, the atomic mass of the middle element is approximately the average of the other two elements. This is known as the Law of Triads. This classification was applicable to very few elements and so it was rejected. For example: New Lands Law of Octaves: He arranged the elements in increasing order of their atomic weights and showed that the properties of every eight elements were similar to those of the first one. The relationship is just like the resemblance of first and eighth musical notes. He named this the Law of Octaves. But his classification was rejected since the law of octaves was applicable to elements up to calcium. The properties of the eighth element become not similar for the rest of the element. Classification Of Elements And Periodicity In Properties Mendeleev’s Periodic Law: Dimitri Mendeleev classified the elements in the increasing order of their atomic weights. He founded that the properties of elements repeat after a regular interval. Based on this observation, he...

CBSE Study Material • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • CBSE Class 11 Chemistry Chapter 3 Notes:Classification of Elements and Periodicity in Properties In this chapter, we will discuss the development of the periodic table and the periodic law. The arrangement of elements in the modern periodic table is organized into eight vertical columns (groups) and seven horizontal rows (periods) based on their atomic number. For more information on Periodic Table, watch the below videos Based on the electronic configuration, elements can be classified into four types in the periodic table, viz s-block, p-block, f-block, and Also Read: • • • Periodic Trends in Properties of Elements • Atomic sizes– With the increase in atomic number, the atomic radii in the group will increase. On the other hand, the atomic radii decrease from left to right in a period. • Ionization enthalpies– Decreases down a group but increases across a period. • Electron gain enthalpies– Tends to become less negative down a group and more negative across a period. • Ele...

Classification of Elements and Periodicity in Properties : Notes and Study Materials -pdf Classification of Elements and Periodicity in Properties NEET and AIIMS Special Classification of Elements and Periodicity in Properties Refresher Course Classification of Elements and Periodicity in Properties : Master File Classification of Elements and Periodicity in Properties : Quick Revision Notes Classification of Elements and Periodicity in Properties : Brain Map About this unit Modern periodic law and long form of periodic table, periodic trends in properties of elements- atomic radii, ionic radii, ionization enthalpy, electron gain enthalpy, electronegativity, valence. Moseley formed the basis of the modern periodic law. He discovered that the square root of the frequency of the more prominent X-rays emitted by a metal was proportional to the atomic number and not the atomic weight of the atom of the metal. Hence atomic number should be the basis of classification of the elements. The f-block elements comprise two horizontal rows placed at the bottom of the periodic table to avoid its un-necessary expansion and make the symmetrical nature of periodic table. The two series of f-block elements containing 14 elements each. Lanthanides – The 14 elements from 58Ce–71Lu in which 4f-subshell is being progressively filled up are called lanthanides or rare earth elements. Actinides – Similarly, the 14 elements from 90Th –103Lr in which 5f-subshell is being progressively filled up are...