Mendeleev’s Periodic Table

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Very Short Answer Type Questions:

  1. How many elements were known at the time of Mendeleev?
  2. In Mendeleev’s Periodic Table, hydrogen was placed along with which type of elements?
  3. Write Mendeleev’s Periodic Law.
  4. What is the formula for sulphide of hydrogen?
  5. What is the formula for sulphide of sodium?

Fill in the blanks:

  1. Mendeleev arranged elements in increasing order of …………………
  2. Mendeleev helped in the foundation of first …………………….in Russia.
  3. Both halogen and hydrogen exist as ………….molecules.
  4. Hydrogen and halogen combine with ……………..to form covalent bonds.
  5. Hydrogen combines with metals to form ……………bonds.

Write True/False for the following:

  1. Hydrogen’s position is controversial in Mendeleev’s Periodic Table.
  2. In Mendeleev’s Periodic Table no element with higher atomic mass was placed before any other element with lower atomic mass.
  3. Two atoms of hydrogen combine with one atom of oxygen to form an oxide.
  4. One atom of sodium combines with one atom of oxygen to form an oxide.
  5. Four atoms of hydrogen combine with one atom of carbon to make a compound.

Short Answer Type Questions:

  1. Write the formulae for chloride, oxide and sulphide of hydrogen.
  2. What are the similarities between hydrogen and halogens?
  3. Why did Mendeleev leave some gaps in his periodic table? How was he proven correct by doing so?
  4. Make a table to show comparisons between properties of Eka-aluminium and gallium.

Long Answer Type Questions:

  1. Discuss some salient features of Mendeleev’s Periodic Table.

Multiple Choice Questions

  1. How many groups are present in Mendeleev’s Periodic Table?
  • a. 8
  • b. 10
  • c. 12
  • d. 16
  1. How many periods are present in Mendeleev’s Periodic Table?
  • a. 2
  • b. 4
  • c. 6
  • d. 8
  1. In Mendeleev’s Periodic Table, how many periods were divided into two series?
  • a. One
  • b. Three
  • c. Five

  • d. Two
  1. In Mendeleev’s Periodic Table, halogens are placed in which group?
  • a. Group VII
  • b. Group VIII
  • c. Group V
  • d. Group IV
  1. Alkaline elements are placed in which group in Mendeleev’s Periodic Table?
  • a. Group VIII
  • b. Group V
  • c. Group III
  • d. Group I

Brainstorming Session

  1. Make a table to compare properties of eka-boron and scandium.
  2. What are isotopes? Why could isotopes not fit in Mendeleev’s Periodic Table?

ANSWER 

Very Short Answer Type Questions:

  1. Answer: 63
  2. Answer: Alkali metals
  3. Answer: Properties of elements are a periodic function of their atomic masses.
  4. Answer: H2S
  5. Answer: Na2S

Fill in the blanks:

  1. Answer: Atomic mass
  2. Answer: Oil refinery
  3. Answer: Diatomic
  4. Answer: Non-metals
  5. Answer: Ionic

Write True/False for the following:

Answer: 1 → T, 2 → F, 3 → T, 4 → F, 5 → T

Short Answer Type Questions:

  1. Answer: Chloride of hydrogen: HCl

Oxide of hydrogen: H2O

Sulphide of hydrogen: H2S

  1. Answer: Both hydrogen and halogens exist as diatomic molecules, e.g. H2 and Cl2. Both of them combine with nonmetals to form covalent bonds, e.g. methane and carbon tetrachloride.
  2. Answer: Mendeleev left some gaps in his periodic table. Those gaps were left to accommodate certain elements which were not known until his time. Mendeleev had predicted discoveries of such elements. Mendeleev named those unknown elements by using the prefix ‘EKA’ before some existing elements. For example; Mendeleev named those elements as Eka-boron, Eka-aluminium and Eka-silicon. Scandium, gallium and germanium; discovered later; show properties of elements mentioned by Mendeleev.
  3. Answer:
Properties of eka-aluminium and gallium
Property Eka-aluminium Gallium
Atomic mass 68 69.7
Formula of Oxide E2O3 Ga2O3
Formula of Chloride ECl3 GaCl3

 

Long Answer Type Questions:

  1. Answer: Some salient features of Mendeleev’s Periodic Table are as follows:
  • In order to group certain elements with similar chemical properties, Mendeleev placed some elements with higher atomic masses before the elements with lower atomic masses. For example; cobalt was placed before nickel. Atomic mass of cobalt is 58.9, while that of nickel is 58.7.
  • Mendeleev left some gaps in his periodic table. Those gaps were left to accommodate certain elements which were not known until this time. Mendeleev had predicted discoveries of such elements. Mendeleev named those unknown elements by using the prefix ‘EKA’ before some existing elements.
  • The striking similarity of new elements’ properties as per Mendeleev’s prediction gave him a lot of respect among the scientific community. His periodic table was widely accepted by the scientists from around the world.
  • Noble gases; like helium, neon and argon were not discovered till his time. However, these gases had been mentioned by some earlier scientists. After their discovery, these gases could be easily fit in the Mendeleev’s Periodic Table without disturbing the original order. This was one of the strengths of Mendeleev’s Periodic Table.

Multiple Choice Questions

  1. Answer: (a) 8
  2. Answer: (c) 6
  3. Answer: (b) Three
  4. Answer: (a) Group VII
  5. Answer: (d) Group I

Brainstorming Session

  1. Answer:
Properties of eka-boron and scandium
Property Eka-boron Sandium
Atomic mass Between 40 to 48 44.95
Formula of Oxide E2O3 Sc2O3
Formula of Chloride ECl3 ScCl3

 

  1. Answer: Elements with same atomic number but different atomic masses are called isotopes. In Mendeleev’s Periodic Table, a particular slot for the element was based on atomic mass. This means an element with a particular atomic mass could be placed in one slot. A slot could not accommodate more than one atomic mass. Hence, isotopes could not fit in Mendeleev’s Periodic Table.

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