Periodic classification of elements: Class 10 Chemistry Q&A · Page 4
96 free answers on Periodic classification of elements (Chemistry) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ChemistryClass 10ICSE
Which of the following statement is correct in regard to the classification of elements ? (a) Elements in the periodic table are arranged on the basis of increasing atomic masses (b) Elements in Mendeleev’s periodic table are arranged on the basis of increasing atomic numbers (c) In modern periodic table, the element nickel of lower atomic mass is kept before the element cobalt of higher atomic mass (d) In modern periodic table, the isotopes of chlorine having diffrenet atomic masses are kept in the same group.
Option (d) is the answer.
- ChemistryClass 10ICSE
• The atomic numbers of four elements P, Q, R and S are 6, 18, 14 and 16 respectively. Out of these, the element known as metalloid is: (a) P (b) Q (c) R (d) S
Option (c) is the answer.
- ChemistryClass 10ICSE
• element X is 14 and that of element Y is 46,then the atomic mass of Element Z will be: (a) 28 (b) 60 (c) 78 (d) 72
Option (c) is the answer.
- ChemistryClass 10ICSE
• In Mendeleev’s periodic table, gaps were left for the elements to be discovered later on. An element which found a vacant place in the periodic table later on is: (a) Be (b) Si (c) Ge (d) Se
Option (c) is the answer.
- ChemistryClass 10ICSE
The three elements having chemical symbols of Si, B and Ge are: (a) All metals (b) All non-metals (c) All metalloids (d) Si is metalloid and Ge is non-metal
Option is (c) is the answer.
- ChemistryClass 10ICSE
According to Mendeleev’s periodic law, the elements were arranged in the periodic table in the order of: (a) Decreasing atomic numbers (b) Increasing atomic numbers (c) Decreasing atomic masses Increasing atomic masses
Option(d) is the answer.
- ChemistryClass 10ICSE
• The Newland’s law of octaves for the classification of elements was found to be applicable only up to the element: (a) Potassium (b) Calcium (c) Cobalt Phosphorus
Option (b) is the answer.
- ChemistryClass 10ICSE
In Mendeleev’s periodic table, gap was not left for one of the element. This element is: (a) Gallium (b) Beryllium (c) Germanium Scandium
Option (b) is the answer.
- ChemistryClass 10ICSE
State modern periodic law. (b) How does the electronic configuration of the atom of an element relate to its position in the modern periodic table? (c) How could the modern periodic law remove various anomalies of Mendeleev's periodic table? Explain with examples. (d) Is it possible to have an element having atomic number 1.5 placed between hydrogen and helium ? Name the scientist who prepared modern periodic table.
The modern periodic law states that the properties of elements are a periodic function of their atomic The elements are arranged in the increasing order of atomic number and helps in arranging the elements according to their electronic Elements across a period show an increase in the number of valence electrons. Anomalies of Mendeleev’s periodic table Elements are arranged in increasing order of atomic number in modern periodic table, thus there was
- ChemistryClass 10ICSE
State Mendeleev's periodic law. (a) What chemical properties of elements were used by Mendeleev in creating his periodic table? (b) State any three limitations of Mendeleev's classification of elements. (c) Besides gallium, which two other elements have since been discovered for which Mendeleev had left gaps in his periodic table ? Which group of elements was missing from Mendeleev's original periodic table?
The properties of elements are a periodic function of their atomic It was the discovery of atomic number which led to a change in Mendeleev's periodic law which was based on atomic mass. The elements having similar chemical properties form oxides and hydrides having similar Mendeleev used these properties for creating his periodic table. Limitations of Mendeleev’s classification of elements: Failed to explain the position of Wrong order of
- ChemistryClass 10ICSE
Why do we classify elements? (b) What were the two criteria used by Mendeleev to classify the elements in his periodic table? (c) Why did Mendeleev leave some gaps in his periodic table? (d) In Mendeleev's periodic table, why was there no mention of noble gases like helium, neon and argon? (e) Would you place the two isotopes of chlorine, Cl-35 and Cl-37 in different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.
The elements are classified according to the properties possessed by the elements. Similar properties falls in same group and thus large number of elements reduced to a few group and orderly arranged. (b)(i) Increasing atomic masses (ii) Grouping together of elements having similar properties. In order to make sure that the elements having similar properties fell in the same vertical column or group, Mendeleev left some gaps in his periodic table. <
- ChemistryClass 10ICSE
How do the properties of eka - aluminium element predicted by Mendeleev compare with the actual properties of gallium element? Explain your answer. What names were given by Mendeleev to the then undiscovered elements (i) scandium (ii) gallium, and (iii) germanium?
Eka-aluminium and gallium are the two different names for a single Eka-aluminium has same property like density, melting point etc as gallium element. (i) Eka Eka Eka-silicon.
- ChemistryClass 10ICSE
State the merits of Mendeleev's classification of elements. (b) Describe two anomalies of Mendeleev's periodic classification of elements.
Merits; Predicted the existence of certain elements such as gallium, scandium and Predicted the properties of various elements based on their positions in the periodic table Mendeleev’s periodic table could place group 18 elements called noble gases in the periodic (b)1.This could not explain the position of isotopes having same chemical properties but different atomic masses. So the isotopes of same element should be given different place in period
- ChemistryClass 10ICSE
(a) State the periodic law on which Mendeleev's periodic table was based. Why and how was this periodic law changed ? (b) Explain why, the noble gases are placed in a separate group.
(a) According to Mendeleev's periodic law: The properties of elements are a periodic function of their atomic masses. It was the discovery of atomic number which led to a change in Mendeleev's periodic law which was based on atomic mass. (b) Noble gas are chemically inert or unreactive so they are placed in different group.
- ChemistryClass 10ICSE
Did Dobereiner's triads also exist in the columns of Newlands' law of octaves? Explain your answer. (b) What were the limitations of Dobereiner's classification of elements? What were the limitations of Newlands' law of octaves?
Yes, Dobereiners triads also exist in the columns of Newlands' Octaves. This can be explained by taking the second column of the Newland’s classification of elements,it has the elements Lithium, Sodium and potassium which form a Dobereiner’s triad. The main limitation of Dobereiner's classification of elements was that it failed to arrange all the then known elements in the form of triads of elements having similar chemical properties an also failed to explain the
- ChemistryClass 10ICSE
What is Newlands' law of octaves? Explain with an example.
According to the Newlands' law of octaves, when elements are arranged in the order of increasing atomic masses, the properties of the eighth element (starting from a given element) are a repetition of the properties of the first element. For example: Lithium is the first element having valence electron 1 and we find the eighth element from it is sodium having similar properties of lithium.
- ChemistryClass 10ICSE
What is Dobereiner's law of triads? Explain with the help of one example of a Dobereiner's triad.
According to Dobereiner’s Law of triads, when elements are arranged in increasing order of their atomic masses, a group of elements with similar chemical properties is obtained. This is called triads. The atomic mass of the middle element is equal to the arithmetic mean of the atomic masses of the other two elements. For example: Calcium, strontium and barium has atomic masses 40,088 and 137 forms a triad and have similar chemical properties. The atomic mass of strontium is appr
- ChemistryClass 10ICSE
Name three elements that have a single electron in their outermost shells. (b) Name two elements that have two electrons in their outermost shells. Name three elements with completely filled outermost shells.
Lithium, Sodium, Potassium are the elements having single electron in their outermost Magnesium, Calcium has two electrons in the outermost shell Helium, Neon, Argon are completely
- ChemistryClass 10ICSE
On which side of the periodic table will you find metals? (b) On which side of the periodic table will you find non-metals? What is the name of those elements which divide metals and non-metals in the periodic table?
Metals are in left side of the periodic table Non-metals are in right side of the periodic table Metalloids is the name of those elements which divide metals and non-metals in periodic
- ChemistryClass 10ICSE
• (a) How were the positions of isotopes of an element decided in the modern periodic table? (b) How were the positions of cobalt and nickel resolved in the modern periodic table? Where should hydrogen be placed in the modern periodic table? Give reason for your answer.
Isotopes have same atomic number and different atomic mass, So they are not given separate place in periodic table and is based on the atomic number of elements. Elements are arranged in the increasing order of their atomic masses as per the Mendeleev’s classification. Cobalt has higher atomic mass was placed before nickel. It has atomic mass of 58.9 and Nickel has 7. In modern periodic table, elements are arranged in the increasing order of therir atomic numbers and he