Tag: development of the modern periodic table

Questions Related to development of the modern periodic table

The properties of the elements, as well as the formulae and properties of their compounds, depend in a periodic manner on the atomic weights of the elements. This periodic law was given by:

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. J. Lothar Meyer

  2. John A.R. Newlands

  3. Dobernier

  4. D. I. Mendeleev

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Correct Option: D

The anomalous pairs in Mendeleev's periodic table is/are_______.

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. Co, Ni

  2. Te, I

  3. Ar, K

  4. All the above

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Correct Option: D
Explanation:

Anomalous pairs in mendeleev's periodic table are
`
Cu,Ni,Te,I,Ar,K

Anomalous pairs are of consecutive elements. Thus if we observe Mendeleev's periodic table, all the given options form anomalous pairs.

In the modified Mendeleev's  periodic table,____ group and_periods are present, whereas in the modern periodic table,groups and___periods are present, respectively:

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. 9, 8, 18, 7

  2. 7, 9, 18, 7

  3. 9, 7, 18, 8

  4. 8, 7, 18, 7

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Correct Option: D
Explanation:

In the modified Mendeleev's periodic table, 8 groups and 7 periods are present, whereas in modern periodic table, 18 groups and 7 periods are present, respectively.

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

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. Copper

  2. Iron

  3. Zinc

  4. Cobalt

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Correct Option: D
Explanation:

Cobalt was placed before nickel despite having atomic mass greater than that of nickel to maintain the periodicity in chemical properties.

Which of the following is a defect in the Mendleev's periodic table?

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. Prediction of new elements

  2. Doubtful atomic weights

  3. Anomalous position of hydrogen

  4. Non-systematic study of elements

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Correct Option: C
Explanation:

Position of hydrogen was not right in the Mendleevs' periodic table. It was placed in IA. However, it resembles the elements of both IA(alkali metals) and group VII A (halogens).

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

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. True,True

  2. True, False

  3. False, True

  4. False, False

Show answer
Correct Option: D
Explanation:

Since, Mendeleev's classification is based on atomic weights, position of isotopes was not given. Lanthanides and Actinides were not known at that time. Their position has not been defined in the periodic table.

Among the following, which are not given a proper place in periodic table?

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. Alkali earth metals

  2. Lanthanides

  3. Actinides

  4. Both B and C

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Correct Option: D
Explanation:

Fourteen elements that follow lanthanum called lanthanides and fourteen elements following actinium called actinides were not given proper places in Modern  periodic table.

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

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. No proper position for hydrogen is given.

  2. Grouping of chemically dissimilar elements.

  3. Position given to isotopes.

  4. Presence of anomalous pairs.

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Correct Option: A,B,C,D
Explanation:
1. Mendeleev could not assign a correct position to hydrogen in the periodic table as hydrogen resembles alkali metals as well as halogens.
2.     Isotopes had to be given the same position in the periodic table though isotopes of the same elements have different atomic masses. 
3.  It was observed that at certain places, an element of higher atomic mass Cobalt (Co=58.93) has been placed before an element of lower atomic mass Nickel (Ni = 58.71).
4. Some elements placed in the same sub - group varies in their properties. Manganese is placed with halogens which totally differ in the properties. 

The Russian chemist Dmitri Mendeleev is generally credited with organizing the chemical elements into a comprehensive periodic table in large part due to the fact that he was able to use his table to predict the existence of elements, like gallium, that were not known at the time $(1872)$, but were discovered later.
Which is the best explanation for why Mendeleev was unable to predict the existence of the noble gases (group $18$)?

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. Noble gases are not found on Earth.

  2. Noble gases are stable and very unreactive, and therefore, have few observable properties.

  3. Noble gases are synthetic elements and do not occur naturally.

  4. Noble gases are very reactive and do not exist as stable elements.

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Correct Option: B
Explanation:

The noble gases are chemically stable and hence usually very unreactive. Thus their properties are very difficult to observe. Hence Mendeleev was unable to predict their existence. Option B

 Which of the following elements position's was not justified in Mendeleev's periodic table?

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. Hydrogen

  2. Lithium

  3. Sodium

  4. Potassium

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Correct Option: A
Explanation:

The position of hydrogen was not justified in Mendeleev's periodic table. He positioned hydrogen in the first column above alkali metal. Hydrogen resembles not only alkali metals but also halogens in several ways. Hence, hydrogen can also be placed above the halogen group.