periodic tables

Long Form of the Periodic Table or Modern Periodic Table - With developments on the structure of atoms, it was discovered that the atomic number (Z) is the important characteristic of the atom and not the atomic mass. This led to the development of the modern..

With developments on the structure of atoms, it was discovered that the atomic number (Z) is the important characteristic of the atom and not the atomic mass. This led to the development of the modern periodic law by Moseley in 1942. The modern periodic law states that "th..

Mendeleev's periodic table was one of the greatest achievements in chemistry with some of its important contributions as follow..

Hydrogen is the first element of the periodic table. Its atomic number is 1, which indicates the presence of only one electron in the atom of hydrogen. This electron is present in its first shell. Hydrogen resembles both alkali metals (group I A) as well as halogens (group VII A..

Mendeleev's Periodic Table - In 1869, Mendeleev classified the then known 56 elements on the basis of their physical and chemical properties by giving a law known as the periodic law. The name periodic law stems from the fact that the properties of the elemen..

Modern Periodic Table-Long Form Periodic Table of Elements - Later, Henry Gywn-Jeffreys Moseley showed that the atomic number of an element is numerically equal to the number of electrons round the nucleus. The number of electrons in turn is equal to the numb..

In 1869, Mendeleev classified the then known 56 elements on the basis of their physical and chemical properties by giving a law known as the periodic law. The name periodic law stems from the fact that the properties of the elements orderly recur in a cyclic fashion. His pe..

Main Features of Modern Periodic Table - 1. The modern periodic table is divided into two main categories: (i) Vertical columns called Groups and (ii) Horizontal columns called Periods. 2. There are 18 vertical columns or groups. These are further s..

Covalent Compounds and Periodic Table - Covalent compounds are formed by the sharing of electrons by atoms of non-metallic elements between groups IVA and VIIA. The elements of these groups react with one another by sharing election pairs. Thus, the valency of an element in a co..

In spite of the above advantages, Mendeleev's periodic table suffered defects as follows: The position of hydrogen was not correctly defined. It was placed in group I although it resembles both the group I elements - the alkali metals and the group VII elements-the halogens, ..