Tag: the periodic table

Questions Related to the periodic table

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.

Show answer
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.

Which of the following was one of the limitations of 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. The discovery of isotopes

  2. The discovery of Noble gases

  3. The discovery of metalloids

  4. None of the above

Show answer
Correct Option: A
Explanation:

The discovery of isotopes was one of the limitations of Mendeleev's periodic table. Since Mendeleev's periodic table was based on atomic masses of elements, isotopes should be placed in different columns despite the fact that they represent the same element.

Novel gases were placed in a group of Mendeleev's periodic table called zero group.
Hence, correct option is $A$.

Mendeleev arranged the known elements in a/an  ______ order of their atomic masses.

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. increasing

  2. decreasing

  3. random

  4. none of the above

Show answer
Correct Option: A
Explanation:

Mendeleev arranged the known elements in an increasing order of their atomic masses. According to Mendeleev's periodic law, the properties of elements are a periodic function of their atomic masses.

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?

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. Germanium

  2. Chlorine

  3. Oxygen

  4. Silicon

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Correct Option: A
Explanation:

Chlorine, oxygen and silicon were included in Mendeleev's periodic table. Germanium was discovered later which fit into the empty spaces left by Mendeleev and matched to the expected properties. 

The elements which have taken the place of Eka aluminium is :

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. Germanium

  2. Gallium

  3. Silicon

  4. Aluminium

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Correct Option: B
Explanation:

Eka-silicon means germanium. It occurred because of silicon whereas eka-aluminium occurred because of aluminium and later named it as gallium. 


While filling the elements considering atomic number would be main and fundamental property there were gaps in the mentioned groups hence he filled them with these names.

Hence the correct option is B.

Which group of elements could be placed in Mendeleev's Periodic Table without disturbing the original order?

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 metals

  2. Alkaline earth metals

  3. Non - metals

  4. Noble gases

Show answer
Correct Option: D
Explanation:

According to Mendeleevs classification, the properties of elements are the periodic function of their atomic masses and there is a periodic recurrence of elements with similar physical and chemical properties. Noble gas being inert, could be placed in a separate group without disturbing the original order.

Mendeleev classified elements in:

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. increasing order of atomic groups.

  2. seven periods and eight groups.

  3. seven periods and nine groups

  4. eight periods and seven groups.

Show answer
Correct Option: B
Explanation:

Mendeleev kept elements in increasing order of atomic weights in seven periods and eight groups.
Therefore, option $B$ is correct. 

The elements whose atomic weight was corrected by Mendeleev 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. Uranium.

  2. Indium

  3. Beryllium

  4. All of these

Show answer
Correct Option: D
Explanation:

Mendeleev described the elements according to both atomic weight and valency. 


The elements if arranged according to their atomic weights exhibit periodicity of properties.

He corrected the atomic weights of thorium, indium, beryllium, and uranium.

Option D is correct.

Most transition metals from multiple cations, that is, they have more than one possible amount of positive charge. Virtually all of the transition metals form dipositive $(2+)$ cations, along with one or more other forms. For example, titanium forms $Ti^{2+}$ ad $Ti^{4+}$, and cobalt forms $Co^{2+}$ and $Co^{3+}$.
The principal exceptions to this predominance of cations with a $2^{+}$ charge are scandium and yttrium, which form only tripositive cations. $Sc^{3+}$ and $Y^{3+}$, and copper and silver, which form cations with a single positive charge. $Cu^{+}$ and $Ag^{+}$.
[While copper also forms dipositive $Cu^{2+}$, silver exhibits the single positive state essentially exclusively.]
Which of the following offers a POSSIBLE explanation for the existence of $Cu^{+}$ and $Ag^{+}$?

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. Mendeleev placed copper and silver in Group IB on his original periodic table because they formed compounds with the same combining ratios as elements in Group $1A$.

  2. Elemental copper and silver have a single valence electron, which is lost in cation formation.

  3. Copper and silver have higher ionization energies than the other transition metals in their respective periods, so are unable to lose more than one electron.

  4. The loss of one electron gives copper and silver noble gas configurations.

Show answer
Correct Option: B
Explanation:

Configuration of Cu and Ag is $\left[ Ar \right] 3{ d }^{ 10 }4{ s }^{ 1 }$ and $\left[ Kr \right] 4{ d }^{ 10 }5{ s }^{ 1 }$ respectively. Thus both have $1$ valence electron which is lost in cation formation. Thus correct answer is option B.