Chemistry

Periodic Classification and Elements

1,176 Questions

Periodic classification organizes chemical elements based on atomic structure, periodic laws, and elemental properties. It covers historical classification systems, electron configurations, and periodic trends. Test takers preparing for chemistry sections will find these questions crucial for mastering fundamental element properties and atomic interactions.

Periodic table structureAtomic orbitalsElement identificationPeriodic laws

Periodic Classification and Elements Questions

Multiple choice 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

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
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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

Multiple choice 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

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

  1. Prediction of new elements

  2. Doubtful atomic weights

  3. Anomalous position of hydrogen

  4. Non-systematic study of elements
Reveal answer Fill a bubble to check yourself
C Correct answer
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).

Multiple choice 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

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.

  1. True,True

  2. True, False

  3. False, True

  4. False, False
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

Multiple choice 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

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

  1. Alkali earth metals

  2. Lanthanides

  3. Actinides

  4. Both B and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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

Multiple choice 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

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.
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
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. 

Multiple choice 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

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 $18$)?

  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.
Reveal answer Fill a bubble to check yourself
B Correct answer
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

Multiple choice 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

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

  1. Hydrogen

  2. Lithium

  3. Sodium

  4. Potassium
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

Multiple choice 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

Which of the following was one of the limitations of Mendeleev's periodic table?

  1. The discovery of isotopes

  2. The discovery of Noble gases

  3. The discovery of metalloids

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $A$.

Multiple choice 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

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

  1. increasing

  2. decreasing

  3. random

  4. none of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

Multiple choice 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

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?

  1. Germanium

  2. Chlorine

  3. Oxygen

  4. Silicon
Reveal answer Fill a bubble to check yourself
A Correct answer
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. 

Multiple choice 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

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

  1. Alkali metals

  2. Alkaline earth metals

  3. Non - metals

  4. Noble gases
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

Multiple choice 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

Mendeleev classified elements in:

  1. increasing order of atomic groups.

  2. seven periods and eight groups.

  3. seven periods and nine groups

  4. eight periods and seven groups.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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

Multiple choice 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

The elements whose atomic weight was corrected by Mendeleev are _______

  1. Uranium.

  2. Indium

  3. Beryllium

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

Multiple choice 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

How many elements were known when Mendeleev presented the periodic table?

  1. 63

  2. 80

  3. 93

  4. 102
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
63 elements were known during the time of the introduction of the Mendeleev periodic table.

During Mendeleev's work, only 63 elements were known.

Option A is correct.
Multiple choice 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

Mark the group which has maximum number of element in Mendeleev's periodic table:

  1. $I$
  2. $II$
  3. $III$
  4. $IV$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In Mendeleev's original periodic table, Group I contained the alkali metals and was quite extensive, often holding more elements than other groups in the early versions.