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प्रश्न
Write scientific reason.
Mendeleev kept vacant places in the periodic table.
उत्तर
- In Mendeleev’s periodic table, the elements are arranged in increasing order of their atomic masses such that chemically similar elements are placed together in a group.
- However, while arranging the elements, Mendeleev kept vacant places in the periodic table for elements not discovered till then.
- Three of these unknown elements were given the names eka-boron, ekaaluminium and eka-silicon from the known neighbours.
- The atomic masses of these elements were indicated as 44, 68 and 72, respectively. He also predicted their properties.
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संबंधित प्रश्न
What are the main features of Mendeleev’s periodic table?
Name two elements that have two electrons in their outermost shells.
By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristic?
State any three demerits of Mendeleev’s periodic table.
On what basis elements are arranged in periodi table now?
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 were the two criteria used by Mendeleev to classify the elements in his periodic table?
State Mendeleev's periodic law.
What chemical properties of elements were used by Mendeleev in creating his periodic table?
(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.
List two contrasting visible characters of garden pea Mendel used for his experiment.
Explain in brief how Mendel interpreted his results to show that the traits may be dominant or recessive.
Mendeleev's contributions to the concept of a periodic table laid the foundation for the Modern Periodic Table. Give reasons.
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?
Answer the following question:
Name two elements having a single electron in their outermost shell.
How did Mendeleev arrange the elements in the periodic table?
What were the defects and anomalies in Mendeleeff's Periodic Table and how are they resolved by Moseley?
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.
What physical and chemical properties of elements did Mendeleev consider in compiling 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 ______
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 ______
Which of the following properties does not match the element of the halogen family?
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.
Write the formulae of chlorides of Eka-silicon and Eka-aluminium, the elements predicted by Mendeléev.
Give an account of the process adopted by Mendeléev for the classification of elements. How did he arrive at “Periodic Law”?
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?
