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

Which element was not known when Mendeleev gave his classification?

  1. Germanium

  2. Gallium

  3. Scandium

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The elements which were unknown when Mendeleev gave his classification were geranium, gallium and scandium. He left gaps for the unknown elements and predicted correctly the properties of some of the unknown elements.

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 having more masses were placed before elements having lower masses in Mendleev's periodic table. Guess the pair of elements (higher mass, lower mass).

  1. Cobalt, Nickel

  2. Vanadium, Chromium

  3. Tellurium, Iodine

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The elements having more masses were placed before elements having lower masses were cobalt, vanadium, tellurium. Its corresponding elements were nickel, chromium and iodine.

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

_______ were not given separate place in periodic table.

  1. Alkali metals

  2. Isotopes

  3. Halogens

  4. Non-metals
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

There were many demerits in the Mendeleevs periodic table like Isotopes had to be given the same position in the periodic table though isotopes of the same elements have different 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

Isotopes could find a position in Mendeleev's periodic table.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mendeleev's periodic table failed because he couldn't tell about the position of isotopes, as he arranged elements on the basis of their increasing atomic mass.

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, the elements were arranged in the increasing order of their atomic masses. However, cobalt with atomic mass of 58.93 amu was placed before nickel having an atomic mass of  58.69 amu. Reason for the same is that :

  1. the elements with similar size can be grouped together

  2. the elements with different properties can be grouped together

  3. the elements with similar properties can not be grouped together

  4. the elements with similar properties can be grouped together
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

According to Mendeleev's 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.

Hence the correct option is D.

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 element eka-silicon predicted by Mendeleev is :

  1. Ge

  2. Ga

  3. Al

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

Eka-silicon is germanium, whereas eka-aluminium is gallium. Here germanium has 4 electrons in its outer most shell, hence it shares electron with chlorine, that too with 4. In case of gallium, it has three unpaired electrons in its outer most shell.

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 did Mendeleev predict the existence of some yet to be discovered elements in his periodic table?

  1. Gaps

  2. Atomic number

  3. Mass number

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

Professor Dmitri Mendeleev published the first periodic table of the atomic elements in 1869 based on properties which appeared with some regularity as he laid out the elements from lightest to heaviest. When Mendeleev proposed his periodic table, he noted gaps in the table, and predicted that as-of-yet unknown elements existed with properties appropriate to fill those gaps.

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 elements in increasing order of their atomic masses and according to their physical properties.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In 1869, just five years after Newlands put forward his Law of Octaves, a Russian chemist called Dmitri Mendeleev published a periodic table. Mendeleev also arranged the elements known at the time in order of relative atomic mass, but he did some other things that made his table much more successful. Hence he arranged according to atomic masses and their 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

Isotopes could find a position in Mendeleev's periodic table.
State whether the given statement is true or false.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Isotopes could not find a position in Mendeleev's periodic table because those were arranged according to atomic number in the increasing order but isotopes have the same atomic number, all isotopes cannot be fitted in a single box in the periodic table. Hence, given statement is false.

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(are) the merit(s) of Mendeleev's periodic table?

  1. Could also predict the properties of these unknown elements

  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 Correct answer
Explanation
A)Mendeleev could also predict the properties of these unknown elements, on the basis of the properties of the elements lying adjacent to these vacant spaces.

He predicted the presence of three elements. They were named as Eka boron, Eka-aluminium and Eka-silicon. The properties of these three elements were similar to the actual elements discovered later.

Eka-boron was similar to Scandium, Eka-aluminium was similar to Gallium and Eka-silicon was similar to Germanium.

It is the merit of Mendeleev's periodic table and all other options are demerits of it.

B) Some elements placed in the same sub-group varies in the properties. 
     Ex. Manganese is placed with halogens which totally differ in properties.

C) Isotopes had to be given the same position though isotopes of the same elements have different atomic masses.

D) The element of higher atomic mass ex. Cobalt [58.93u] has been placed before an element of lower atomic mass ex. Nickel [58.71u]. 
     These are anomalous pairs.

Hence, the correct option is $\text{A}$