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प्रश्न
State any three demerits of Mendeleev’s periodic table.
उत्तर
Demerits of Mendeleev’s periodic table:
- Hydrogen resembles alkali metals and halogens. So, a correct position could not be assigned to hydrogen in the periodic table.
- The position of isotopes could not be explained. Isotopes are atoms of the same element with similar chemical properties but different atomic masses. If the elements are arranged according to atomic masses, the isotopes should be placed in different groups of the periodic table.
- At certain places, an element of higher atomic mass has been placed before an element of lower atomic mass. Example: Cobalt (Co = 58.93) is placed before nickel (Ni = 58.71).
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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.
On what basis elements are arranged in periodi table now?
On what basis did mandeleev arrange the elements in his periodic table?
Name the Russian chemist who said that the properties of elements are a periodic function of their atomic masses.
State Mendeleev's periodic law.
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.
Explain in brief how Mendel interpreted his results to show that the traits may be dominant or recessive.
Write the merits of Mendeleev’s periodic table.
State Mendeleev's periodic law.
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?
How many elements were known at the time of Mendeleev's classification of elements?
What are the demerits of Mendeleev’s periodic table?
How did Mendeleev arrange the elements in the periodic table?
What was the basis of Mendeleev's classification?
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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 _______.
According to Mendeleev’s periodic law properties of elements are ______.
While designing the periodic table, Mendeleev considered the chemical and physical properties of the elements.
State Mendeleev’s Periodic Law.
The properties of eka-aluminum predicted by Mendeleev are the same as the properties of a later discovered elements: ______
An element has 12 protons. The group and period to which this element belongs is ______
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According to Mendeléev's Periodic Law, the elements were arranged in the periodic table in the order of
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
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.
Write the formulae of chlorides of Eka-silicon and Eka-aluminium, the elements predicted by Mendeléev.
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 ______.
