merits and demerits of periodic table

The two-kingdom classification received considerable recognition from biologists and was in use for quite a long period of time. However, as more and more information started emerging on the various groups of plants and animals, this system of classification was found to be inadequate. St..

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, ..

Although the long form of the period table has been able to help in systematic studying the elements to a great extent, it has some minor defects: Hydrogen resembles both the alkali metals and halogens. But it has been placed with the alkalis. The lanthanides and actinides..

Merits: 1. Mean deviation is easy to calculate. This measure is simple to understand. 2. This can be calculated from any average. 3. It is less affected by extreme observations. Demerits: 1. This is mathematically incomplete because it ign..

Merits:..

Advantages - The offsprings are genetically identical and therefore advantageous traits can be preserved. Only one parent is required which eliminates the need for special mechanisms such as pollination, etc. It is faster. For example, bacteria can multiply every 20 minutes. This helps the organism..

There are seven periods in the periodic table and each period starts with a different principal quantum number. The first period corresponding to 'n' = 1 consists of only two elements hydrogen (1s 1 ) and helium (1s 2 ). This is because the first e..

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 "the phys..

The modern periodic table is also known as the long form of the periodic table or the extended form of the periodic table..

Position of Hydrogen in the Periodic Table - 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 resemble..