Question

Explain merits and demerits of mendeleev periodic table.

Answer 1

Answer:

Merits of mendeleev periodic table:

• Mendeleev left some gaps in his table, boldly explaining the existence of these elements, with same atomic number and property, he named them:

eka - Silicon: germanium.

eka - Baron: scandium.

eka - Alluminium : gallium

• Even after the discovery of noble gases, the table was not disturbed as noble gases could be placed in a different group.

Demerits of mendeleev periodic table:

• Hydrogen didn't had the right place, as hydrogen also resembles as alkalimetal and halogens.

• Isoptopes were not given proper place.

• Since, atomic masses didn't increase in the order, he wouldn't predict the number of elements between any two.

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Answer 2

Answer:

Merits and demerits of Mendeleev's periodic table are as follows:

Merits

• In the arrangement, similarity in attributes was given greater importance than atomic mass.
• Atomic mass correction.
• Prediction of new elements.
• Noble gases were also fit well in the table.

Demerits

• Unable to give a proper position to hydrogen.
• The number of elements yet to be discovered was not predictable.
• Isotopes did not fit into the table.

Explanation:

Merits

• Iodine, despite having a lower mass (127) than Tellurium (128), is placed later because it resembles chlorine and bromine more than oxygen and sulphur. Similarly, increasing atomic mass has little effect on cobalt and nickel.
• Elements of beryllium, indium, gold, and platinum were projected to have the wrong mass based on periodic properties, leading to a re-estimation of their true mass.
• It was able to anticipate the existence and qualities of three elements with properties that were comparable to boron, aluminium, and silicon. Eka-boron, Eka-aluminum, and Eka-silicon are the names of these elements. They were isolated and given the names scandium, gallium, and germanium.
• Noble gases might readily be connected to Mendeleev's table because they have inert behaviour and zero valences.

Demerits

• He couldn't locate hydrogen in the periodic chart.
• Moving from one element to the next caused an irregular increase in atomic mass. As a result, the number of elements that have yet to be identified remains unpredictable.
• Later on, isotopes of elements that defied Mendeleev's periodic law were discovered.