Periodic classification of elements: Class 10 Chemistry Q&A · Page 5
96 free answers on Periodic classification of elements (Chemistry) for Class 10 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ChemistryClass 10ICSE
In the modem periodic table, which are the metals among the first ten elements? (b) What is the significance of atomic number in the modern classification of elements? Explain with the help of an example.
(a) In modern periodic table, Lithium and beryllium are metals among the first ten elements. (b) The significance of atomic numbers in the periodic table is the arrangement of elements according to their electronic configuration. The elements placed in same group shows similar chemical properties. Example: Atomic number of lithium is 3 and its electronic configuration is 2,1. It is placed in first group as the valence electron is 1 and sodium has electronic configuration of 2,8,1 havi
- ChemistryClass 10ICSE
a) What is meant by (i) a group, and (it) a period, in a periodic table? (b) How many periods and groups are there in the long form of periodic table? Give two examples each of (i) group 1 elements (ii) group 17 elements (iii) group 18 elements.
Groups are the vertical columns in the periodic table (i) A period is the horizontal rows of elements in the periodic table. There are seven periods and eighteen groups in the long form of [periodic (i) Group 1: Lithium and Group 17: Fluorine and Group 18: Neon and
- ChemistryClass 10ICSE
• Fill in the following blanks with suitable words: (a) The basis for modern periodic table is . (b) The horizontal rows in a periodic table are called . (c) Group 1 elements are called . (d) Group 17 elements are known as . (e) Group 18 elements are called . (f) According to Newlands' classification of elements, the properties of sulphur are similar to those of oxygen because sulphur is the element starting from oxygen.
Atomic Alkali Noble
- ChemistryClass 10ICSE
Which group of elements could be placed in Mendeleev's periodic table later on, without disturbing the original order? Give reason.
Noble gases which are chemically reactive and more stable could be placed in the periodic table in the form of a separate group.
- ChemistryClass 10ICSE
State one example of a Dobereiner's triad, showing in it that the atomic mass of middle element is half-way between those of the other two.
Lithiium, sodium and potassium are said to be triads in the Mendeleev’s periodic table. Lithium is the first element in the triad and sodium being middle has atomic mass of 23 and third element is potassium. Atomic mass of sodium = At. Mass of Li + At. Mass of K / 2 = 7+39/2 =23
- ChemistryClass 10ICSE
Name two elements whose properties were predicted on the basis of their positions in Mendeleev's periodic table.
Eka- Aluminium (gallium) and Eka-Silicon (germanium) are the two elements whose properties were predicted on the basis of their positions.
- ChemistryClass 10ICSE
The three elements predicted by Mendeleev from the gaps in his periodic table were known as eka-boron, eka - aluminium and eka-silicon. What names were given to these elements when they were discovered later on?
Scandium, Gallium, Germanium are the three elements predicted by Mendeleev from the gaps in his periodic table and were known as eka-boron, eka - aluminium and eka-silicon.
- ChemistryClass 10ICSE
10Name two elements whose properties were predicted on the basis of their positions in Mendeleev's periodic table.
Gallium and Scandium are the two elements whose properties are predicted on the basis of their positions in Mendeleev’s periodic table.
- ChemistryClass 10ICSE
• In the classification of the then known elements, Mendeleev was guided by two factors. What are those two factors?
Increasing atomic masses Grouping together of elements having the same
- ChemistryClass 10ICSE
What was the Mendeleev's basis for the classification of elements?
Mendeleev's basis for the classification of elements was the atomic mass of elements.
- ChemistryClass 10ICSE
X and Y are the two elements having similar properties which obey Newlands' law of octaves. How many elements are there in-between X and Y?
Six elements will be there in between X and Y. Since X and Y are the two elements having similar properties and obey Newlands law of octaves.
- ChemistryClass 10ICSE
A, B and C are the elements of a Dobereiner's triad. If the atomic mass of A is 7 and that of C is 39, what should be the atomic mass of B?
Mass of A is 7 Mass of C is 39 Mass of B = 7+39/2 = 23
- ChemistryClass 10ICSE
Name the scientists who gave the following laws in the early classification of elements: Law of octaves (b) Law of triads
Newlands put forth the law of Dobereiner put forth the law of
- ChemistryClass 10ICSE
Name the Russian chemist who said that the properties of elements are a periodic function of their atomic masses.
Mendeleev said that the properties of elements are a periodic function of their atomic masses.
- ChemistryClass 10ICSE
• State whether the following statement are true or false: (a) Newlands divided the elements into horizontal rows of eight element each. (b) According to Mendeleev's periodic law, the properties of elements are a periodic function of their atomic numbers. The elements in a group have consecutive atomic numbers.
Newlands divided the elements into horizontal rows of seven element each. According to Mendeleev’s periodic law, the properties of elements are a periodic function of their atomic masses The elements in a period have consecutive atomic numbers.
- ChemistryClass 10ICSE
On what basis did Mendeleev arrange the element in his periodic table. On what basis are they arranged now?
(a) On the basis of atomic masses Mendeleev arranged the element in his periodic table. (b) Now arranged on the basis of atomic numbers.