(a) What is a group in the periodic table? In which part of a group would you separately expect the elements to have (i) the greatest metallic character (ii) the largest atomic size?
(b) In what respects do the properties of group 1 elements differ from those of group 17 elements? Explain with examples by taking one element from each group.
(c) From the standpoint of atomic structure, what determines which element will be the first and which the last in a period of the periodic table?
(d) Explain why, the properties of elements are repeated after 2, 8, 18, and 32 elements in the periodic table.
(e) What are the advantages of the periodic table?
(a) The vertical columns in a periodic table are called groups.
(i) The greatest metallic character is found in the elements in the lowest part of the group.
(ii) The largest atomic size is found in the lowest part of the group.
(b) Group 1 elements have 1 valence electron. They are ionic in nature. Their chemical reactivity increases down the group.
They are electropositive in nature and it increases down the group.
The elements of group 17 have 7 valence electrons. They are non-metals. Their chemical reactivity decreases down the group. They are electronegative in nature.
(c) The number of valence electrons in the atoms of elements decides which element will be the 1st element in a period and which will be the last in a period.
(d) The properties of elements are repeated after 2, 8, 18, and 32 elements in the periodic table because the electronic configuration of the elements is repeated in this manner.
(e) Advantages of the periodic table are given below:
(i) It has made the study of chemistry systematic and easy.
(ii) It is easier to remember the properties of an element if its position in the periodic table is known.
(iii) The type of compounds formed by an element can be predicted by knowing its position in the periodic table.
(iv) It is used as a teaching aid in chemistry in schools and colleges.
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- (a) What is meant by (i) a group, and (ii) a period, in a periodic table?(b) How many periods and groups are there in the long form of periodic table? (c) Give two examples each of (i) group 1 elements (ii) group 17 elements (iii) group 18 elements.
- Consider the following elements:20Ca, 8O, 18Ar, 16S, 4Be, 2He Which of the above elements would you expect to be: (i) very stable? (ii) in group 2 of the periodic table? (iii) in group 16 of the periodic table?
- What is the atomic number of element of period 3 and group 17 of the Periodic Table?1041721
- (a) How does the electropositive character of elements change on going down in a group of the periodic table?(b) State how the valency of elements varies (i) in a group, and (ii) in a period, of the periodic table.
- What happens to the metallic character of the elements as we go down in a group of the periodic table?
- 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.
- Carbon, Group (14) element in the Periodic Table, is known to form compounds with many elements. Write an example of a compound formed with(a) chlorine (Group 17 of Periodic Table)(b) oxygen (Group 16 of Periodic Table)
- Atomic number of a few elements are given below 10, 20, 7, 14(a) Identify the elements(b) Identify the Group number of these elements in the Periodic Table(c) Identify the Periods of these elements in the Periodic Table(d) What would be the electronic configuration for each of these elements?(e) Determine the valency of these elements.
- (a) What is the usual number of valence electrons and valency of group 18 elements of the periodic table?(b) What happens to the number of valence electrons in the atoms of elements as we go down in a group of the periodic table?
- What property do all the elements in the same group of the periodic table as fluorine have in common?
- 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.
- Consider the following elements:Na, Ca, Al, K, Mg, Li (a) Which of these elements belong to the same period of the periodic table? (b) Which of these elements belong to the same group of the periodic table?
- How does the valency of elements vary in going down a group of the periodic table?
- (a) What is the main characteristic of the last elements in the periods of the periodic table? What is the general name of such elements?(b) What is the number of elements in: (a) 1st period, and (b) 3rd period, of the modern periodic table?
- (a) On which side of the periodic table will you find metals?(b) On which side of the periodic table will you find non-metals? (c) What is the name of those elements which divide metals and non-metals in the periodic table?
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