Limitations of Mendeleev's Periodic Table

Q.

Why did Mendeleev leave gaps in his periodic table? [2 MARKS]

Q.

The serial number of an element in a periodic table is also its …………… , …………….

Q.

In Mendeleev’s Periodic Table the elements were arranged in the increasing order of their atomic masses. However, cobalt with an atomic mass of $58.93$ amu was placed before nickel having an atomic mass of $58.71$ amu. Give a reason for the same.

Q.

Why wasn't hydrogen given a fixed position in Mendeleev’s Periodic Table? [1 MARK]

Q. Isotopes didn't find any place in Mendeleev's periodic table. True or False?

1. True
2. False

Q.

Explain the comparison of Mendeleev and Modern periodic table?

Q.

Mendeleevs periodic table is based upon the atomic masses. This periodic table is upset by the fact that

1. many elements have several isotopes

2. noble gases do not form compounds

3. some groups are divided into two sub groups A and B

4. atomic weights of elements are not always whole numbers

Q. Which of the following are the demerits of Mendeleev periodic table?

1. No proper position for hydrogen is given.
2. Grouping of chemically dissimilar elements.
3. Position given to isotopes.
4. Presence of anomalous pairs.

Q.

Write the formulae of chlorides of Eka-silicon and Eka-aluminium, the elements predicted by Mendeleev.

Q.

In Mendeleevs periodic table, elements are arranged in increasing order of their atomic number

1. True
2. False

Q. The position of hydrogen could not be justified by Mendeleev.

1. True
2. False

Q. Why isotopes cant be inserted in mendaleevs periodic table???

Q. Based on the statements given below, choose the correct one’s regarding limitations of Mendeleev’s periodic table.​
​
I. The position of hydrogen in the periodic table was uncertain.​
II. Isotopes of elements were not given different positions in the table.​
III. In the arrangement of Te and I, the increasing order of atomic mass was not obeyed.​ [1 Mark]

a. Only II is correct​
b. I, II are correct​
c. II, III are correct​
d. I, II, III are correct​

Q. Isotopes were discovered long after Mendeleev had proposed his periodic table.

1. True
2. False

Q. Mendeleev placed isotopes in his periodic table.

1. False
2. True

Q.

Which physical and chemical properties of the elements were used by Mendeleev in creating his periodic table ? List two observation which posed a challenge of Mendeleev's periodic law.

Q. State true or false.
1. Position of isotopes was clearly defined in Mendeleev's periodic table.
2. Position of lanthanides and actinides was clearly defined in Mendeleev's periodic table.

1. True, True
2. True, False
3. False, True
4. False, False

Q. According to Mendeleev's periodic table, one element whose atomic mass is greater than that of nickel is placed before nickel. Name the element.

1. Copper
2. Iron
3. Zinc
4. Cobalt

Q.

Mendeleevs periodic table also suffered from a lot of defects. Answer the following questions in keeping in mind the defects of Mendeleevs periodic table.

Why the position of isotopes was considered a defect?

Q. Which among these are limitations of Mendeleev's periodic table?

1. Position of hydrogen
2. Position of isotopes
3. Similar elements paced separately
   
4. None of These

Q. In certain pair of elements, the increasing order of atomic masses was not obeyed. Is it true according to Mendeleev's periodic table?

1. True
2. False

Q.

In Mendeleevs 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?

1. Germanium

2. Chlorine

3. Oxygen

4. Silicon

Q.

Mendeleev predicted the existence of few undiscovered elements based on his periodic table.

1. True

2. False

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Compare and contrast the arrangement of elements in Mendeleev’s Periodic Table and the Modern Periodic Table.

Q.

(a) Why do we classify elements?

(b) What were the two criteria used by Mendeleev to classify the elements in his periodic table?

(c) Why did Mendeleev leave some gaps in his periodic table?

(d) In Mendeleev’s periodic table, why was there no mention of noble gases like helium, neon and argon?

(e) Would you place the two isotopes of chlorine, $C_{35}Cl$ and $C_{37}Cl$ in different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.

Q.

Why did Mendeleev leave gaps in his periodic table? [2 MARKS]

Q. Assertion :Mendeleev's periodic table have some demerits. Reason: There was no place for all isotopes of the elements and some heavy elements were placed before lighter elements.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q.

State defects of Mendeleevs periodic table.

Q.

Select the limitations of Mendeleev's periodic table from the given options.

1. Some elements with different properties were kept in the same group.

2. The position of Hydrogen was not fixed.

3. The arrangement of elements on the basis of increasing atomic masses was not always followed.

4. Empty spaces were left in the Mendeleev's periodic table in case some new elements were discovered.

Q.

What are the limitations of Mendeleev's periodic table? [5 MARKS]