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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.
Helium is an unreactive gas and neon is a gas of extremely low reactivity. What, if anything, do their atoms have in common?
State any three demerits of Mendeleev’s periodic table.
Name the Russian chemist who said that the properties of elements are a periodic function of their atomic masses.
(a) Write its electronic configuration and determine its valency.
(b) Is it more reactive or less reactive than Ca (atomic number 20)? Justify your answer giving reason.
(c) Is it a metal or a non-metal?
(d) Write the formula of its oxide.
Why did Mendel choose garden pea for his experiments? Write two reasons.
List two contrasting visible characters of garden pea Mendel used for his experiment.
Write the merits of Mendeleev’s periodic table.
Mendeleev's contributions to the concept of a periodic table laid the foundation for the Modern Periodic Table. Give reasons.
Use Mendeleev's Periodic Table to predict the formula of hydrides of carbon and silicon.
Use Mendeleev's Periodic Table to predict the formula of oxides of potassium, aluminum, and barium.
Which group of elements was missing from Mendeleev's original periodic table?
Why did Mendeleev's leave some gaps in his periodic table os elements? Explain your answer with an example.
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.
What were the defects and anomalies in Mendeleeff's Periodic Table and how are they resolved by Moseley?
Give a reason for the following:
Mendeleev's contributions to the periodic table laid the foundation for the Modern Periodic Table.
At the time of Mendeleev _______ elements were known.
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.
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.
State Mendeleev’s Periodic Law.
Distinguish between:
Mendeleev’s periodic table - Modern periodic table
On which basis Mendeleev organised periodic law?
What physical and chemical properties of elements did Mendeleev consider in compiling the periodic table?
Which of the following oxide is most basic?
The total number of electrons present in the first twenty elements of the periodic table is ______
According to Mendeléev's Periodic Law, the elements were arranged in the periodic table in the order of
On moving from left to right in a period in the periodic table, the size of the atom.
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”
State Mendeleev’s Law of Periodicity.
