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प्रश्न
Write a short note.
Mendeleev’s periodic law.
उत्तर
Mendeleev’s periodic law.
- According to Mendeleev’s Periodic Law, “Physical and chemical properties of elements are a periodic function of their atomic masses”.
- Mendeleev classified elements according to their atomic masses and arranged these elements in increasing order of their atomic masses.
- Mendeleev classified the periodic table into horizontal rows and vertical columns. The horizontal rows are called periods and the vertical columns are called groups. Mendeleev’s Periodic Table contains seven horizontal rows and 8 vertical columns.
- The elements with similar properties come into the same group.
- Mendeleev also left gaps in his periodic table for undiscovered elements like aluminium, silicon and Boron in his periodic table and named them Eka-Aluminium, Eka-silicon and Eka-Boron.
- Mendeleev not only predicted the existence of Eka-Aluminium, Eka-silicon and Eka-Boron but also described the general physical properties of these elements.
- These elements were discovered later and named Gallium, Germanium and Scandium.
- Mendeleev's periodic table could predict the properties of several elements on the basis of their position in the periodic table.
- Mendeleev's periodic table could accommodate noble gases when they were discovered.
Demerits of Mendeleev's periodic table:
- The position of isotopes could not be explained.
- The wrong order of atomic masses of some elements could not be explained.
- Position of Hydrogen could not be assigned in a periodic table.
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संबंधित प्रश्न
Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements:
K, C, Al, Si, Ba.
Name two elements that have two electrons in their outermost shells.
Name three elements with filled outermost shells.
Lithium, sodium, potassium are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements?
By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristic?
Element X forms a chloride with the formula XCl2, which is a solid with a high melting point. X would most likely be in the same group of the Periodic Table as
State whether the following statement is true of false:
According to Mendeleev's periodic law, the properties of elements are a periodic function of their atomic numbers.
What chemical properties of elements were used by Mendeleev in creating his periodic table?
Why did Mendel choose garden pea for his experiments? Write two reasons.
Use Mendeleev's Periodic Table to predict the formula of hydrides of carbon and silicon.
Name an element whose properties were predicted on the basis of its position in Mendeleev's periodic table.
Name two elements whose atomic weights were corrected on the basis of their positions in Mendeleev's periodic table.
How many elements were known at the time of Mendeleev's classification of elements?
How did Mendeleev arrange the elements in the periodic table?
State the contributions made by Mendeleev towards the periodic table.
According to Mendeleev’s periodic law, properties of elements are periodic function of their _______.
In Mendeleev’s periodic table eka- silicon was later named as _______.
Write the molecular formula of the oxide of any one of the elements in Mendeleev’s periodic table.
Which two elements show an ambiguity regarding their sequence in Mendeleev’s periodic table?
While designing the periodic table, Mendeleev considered the chemical and physical properties of the elements.
Write scientific reason.
Mendeleev kept vacant places in the periodic table.
What challenges did Mendeleev face in following periodic law?
In Mendeleev’s Periodic Table, gaps were left for the elements to be discovered later. Which of the following elements found a place in the Periodic Table later?
At the time of Mendeleev, the number of elements known was ______
An element has 12 protons. The group and period to which this element belongs is ______
Which of the following are the characteristics of isotopes of an element?
(i) Isotopes of an element have the same atomic masses
(ii) Isotopes of an element have the same atomic number
(iii) Isotopes of an element show the same physical properties
(iv) Isotopes of an element show the same chemical properties
The total number of electrons present in the first twenty elements of the periodic table is ______
In Mendeléev’s Periodic Table, gaps were left for the elements to be discovered later. Which of the following elements found a place in the periodic table later
Which of the following statement (s) about the Modern Periodic Table are incorrect
- The elements in the Modern Periodic Table are arranged on the basis of their decreasing atomic number
- The elements in the Modern Periodic Table are arranged on the basis of their increasing atomic masses
- Isotopes are placed in adjoining group (s) in the Periodic Table
- The elements in the Modern Periodic Table are arranged on the basis of their increasing atomic number
In Mendeléev’s Periodic Table the elements were arranged in the increasing order of their atomic masses. However, cobalt with atomic mass of 58.93 amu was placed before nickel having an atomic mass of 58.71 amu. Give reason for the same.
Properties of the elements are given below. Where would you locate the following elements in the periodic table?
- A soft metal stored under kerosene
- An element with variable (more than one) valency stored under water.
- An element which is tetravalent and forms the basis of organic chemistry
- An element which is an inert gas with atomic number 2
- An element whose thin oxide layer is used to make other elements corrosion resistant by the process of “ anodising”
Mendeléev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.
- Name the elements which have taken the place of these elements
- Mention the group and the period of these elements in the Modern Periodic Table.
- Classify these elements as metals, non-metals or metalloids
- How many valence electrons are present in each one of them?
Mendeleev's periodic table was based on ______.
Name the elements whose compounds formed the basis of classification in Mendeleev's periodic table. Why did Mendeleev choose these elements?
How the formulae of these compounds had helped Mendeleev in deciding the position of an element in his periodic table?
