merits and demerit of mendeleev's periodic table
Answers
Answer:
Merits of Mendeleev Periodic Table
Some gaps were left for the elements yet to be discovered. Thus, if a certain new element is discovered, it can be placed in a new group without disturbing any existing group.
Demerits of Mendeleev Periodic Table
He was unable to locate hydrogen in the periodic table.
Increase in atomic mass was not regular while moving from one element to another. Hence, the number of elements yet to be discovered was not predictable.
Later on, isotopes of elements were found which violated Mendeleev’s periodic law.
Also, Read ⇒ Periodic Trends in Ionization Enthalpy
Frequently Asked Questions
What is the law of the Mendeleev periodic table?
Mendeleev claimed the famous periodic law that “Element properties are a periodic function of their atomic weight.” Mendeleev placed elements in the order of their atomic weights in the form of a table known as the Periodic Table of Mendeleev.
What is the difference between Mendeleev and the modern periodic table?
The main differences are: the periodic table of Mendeleev is based on atomic mass. The current periodic table is based on the number of atoms. Noble gasses (as they are not found at that time) were not included in Mendeleev’s periodic table. In Modern periodic table noble gasses in a separate group called group-18.
How did Mendeleev find atomic mass?
Mendeleev was not himself estimating the atomic mass. He had the information he was working on to see the repeated properties to find a pattern that turned out to be a chart. And he predicted their atomic mass on the basis of the pattern he observed for the atoms that were not detected.
What is Mendeleev famous for?
Mendeleyev is best known for his discovery of the periodic law he adopted in 1869 and the periodic table of elements he developed. He died on February 2, 1907, in St. Petersburg, Russia.
How do u find electrons in the periodic table?
A series of simple rules will determine the number of protons, neutrons, and electrons in an atom. The hydrogen nucleus number of protons is equal to the atomic number (Z). In a neutral atom, the number of electrons is equal to the number
Merits and demerits of Mendeleev's periodic table
Explanation:
Mendeleev's periodic table
Mendeleev established the famous periodic law, which states that "element properties are a periodic function of their atomic weight." Mendeleev organized elements according to their atomic weights in a table known as the Periodic Table of Mendeleev.
Merits of Mendeleev's periodic table
- Iodine, despite having a lower weight (127) than Tellurium (128) is placed later because it resembles chlorine and bromine more than oxygen and sulfur. Likewise, cobalt and nickel do not increase in atomic mass.
- Elements of beryllium, indium, gold, and platinum were projected to have the wrong mass based on periodic properties, leading to a re-estimation of their original mass.
- It was able to predict the occurrence and the presence of three elements with properties similar to boron, aluminum, and silicon. These elements were given the names Eka-boron, Eka-aluminum, and Eka-silicon. They were separated and given the names scandium, gallium, and germanium.
- Noble gases have inert properties and zero valences. They could therefore be attached to Mendeleev's table quite easily. So, they are discovered later.
Demerits of Mendeleev periodic table
Position of hydrogen
- This is the most crucial point. Hydrogen's properties were similar to those of alkali metals and halogens. As a result, the position of hydrogen (whether it should be with halogens or alkali metals) is not specified.
Isotope's position
- Isotopes are elements that have the same atomic number but differ in mass number.
- Mendeleev's periodic table was created to demonstrate the idea of representing elements in increasing order of atomic mass. Isotopes, on the other hand, were not included in his periodic table.
Position of Cobalt and Nickel
- Some elements were arranged in a reversal. Elements with a higher atomic mass were placed in front of those with a lower atomic mass. Cobalt and nickel are two examples.
- Nickel has an atomic mass of 58.71 and cobalt has an atomic mass of 58.93. Because elements were ordered by their atomic masses, Cobalt was placed before Nickel in Mendeleev's periodic table.