Periodic classification of elements: Class 10 Chemistry Q&A · Page 3
96 free answers on Periodic classification of elements (Chemistry) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ChemistryClass 10ICSE
Name the element which is in: (a) First group and third period. Seventeenth group and second period.
Sodium is the element in first group and third period Fluorine is the element in the second period and seventeenth
- ChemistryClass 10ICSE
How does the valency of elements vary in going down a group of the periodic table?
All the elements in a group have the same valency while going down the group.
- ChemistryClass 10ICSE
How does the valency of elements change on moving from left to right in the third period of the periodic table?
The valency of elements changes from left to right by increasing from 1 to 4 and decreases to zero in the 3rd period.
- ChemistryClass 10ICSE
How does the number of valence electrons vary on moving from left to right: (i) In the first period of the periodic table? In the second period of the periodic table?
The number of valence electrons increases from 1 to 2 in the 1st period of the periodic The valence electrons increase from 1 to 8 in the 2nd period of the periodic
- ChemistryClass 10ICSE
Explain why:(i) All the elements of a group have similar chemical properties. (ii) All the elements of a period have different chemical properties. (b) The atomic radii of three elements X, Y and Z of a period of the periodic table are 186 pm; 104 pm and 143 pm respectively. Giving a reason, arrange these elements in the increasing order of atomic numbers in the period.
(a) (a) (i) All the elements of a group have similar chemical properties because they have same number of valence electrons in their outermost shell. (ii) All the elements of a period have different chemical properties because they have different number of valence electrons in their atoms. (b) As the atomic number increases in a period from left to right, the size of atoms goes on decreasing and the order of atomic numbers of elements will be X < Z < Y.
- ChemistryClass 10ICSE
What happens to the metallic character of the elements as we go down in a group of the periodic table?
On going down in a group of the periodic table, the metallic character of elements increases.
- ChemistryClass 10ICSE
How do the atomic radii of elements change as we go from left to right in a period of the periodic table?
On moving from left to right in a period, the atomic size decreases.
- ChemistryClass 10ICSE
What is the major characteristic of the first elements in the periods of the periodic table? What is the general name of such elements?
The first elements in the periods of the periodic table have 1 valence electron. Such elements are called alkali metals
- ChemistryClass 10ICSE
State whether the following statement is true or false: On-going down in a group of the periodic table, the number of valence electrons increases.
False. On-going down in a group of the periodic table, the number of valence electrons remains same.
- ChemistryClass 10ICSE
(a) What is the number of valence electrons in the atoms of first element in a period? (b) What is the usual number of valence electrons in the atoms of the last element in a period?
1 valence electron will be there in the atom of first element in a period 8 valence electron will be there in the atom of last element in the
- ChemistryClass 10ICSE
What property do all the elements in the same group of the periodic table as fluorine have in common?
The element fluorine is in group 17 of the periodic table and has a valency of 1. So, all the elements in the same group of periodic table as fluorine will have a valency of 1.
- ChemistryClass 10ICSE
What property do all elements in the same column of the periodic table as boron have in common?
All elements in the same column of the periodic table as boron have 3 valence electrons.
- ChemistryClass 10ICSE
How does the chemical reactivity of alkali metals vary on going down in group 1 of the periodic table? (b) How does the chemical reactivity of the halogens vary on going down in group 17 of theperiodic table?
(a) In group 1 of alkali metals, the chemical reactivity increases from lithium to francium. (b) In group 17 of halogen elements, the chemical reactivity decreases from fluorine to iodine.
- ChemistryClass 10ICSE
How would the tendency to lose electrons change as we go from left to right across a period of the periodic table.
On moving from left to right in a period, the tendency of atoms to lose electrons decreases.
- ChemistryClass 10ICSE
1. How would the tendency to gain electrons change on moving from left to right in a period of the periodic table?
On moving from left to right in a period, the tendency of atoms to gain electrons increases.
- ChemistryClass 10ICSE
Given alongside is a part of the periodic table: Li Be B C N O F Na Mg Al Si P S Cl As we move horizontally from left to right: (i) What happens to the metallic character of the elements? What happens to the atomic size?
Solution: Metallic character Atomic size
- ChemistryClass 10ICSE
The atomic particle whose number in the atoms of an element always remains the same and which forms the real basis for the modern classification of element is: (a) Electron (b) Proton (c) Neutron Meson
Option (b) is the answer.
- ChemistryClass 10ICSE
The modern periodic table was prepared by : (a) Dobereiner (b) Newland (c) Bohr Mendeleev
Option (c) is the answer.
- ChemistryClass 10ICSE
An element X forms an oxide X2O3. In which group of Mendeleev’s periodic table is this element placed? (a) Group II (b) Group III (c) Group V (d) Group VIII
Option (b) is the answer.
- ChemistryClass 10ICSE
Which of the following statement about modern periodic table is correct? (a) It has 18 horizontal rows known as periods (b) It has 7 vertical columns known as periods (c) It has 18 vertical columns known as groups It has 7 horizontal rows known as groups
Option (c) is the answer.