(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 and are ionic in chemical reactions. Their chemical reactivity increases down the group. They are electropositive in nature and it increases down the group. Whereas, the elements of group 17 have 7 valence electrons. They all are non-metals. Their chemical reactivity decreases down the group. They are electronegative in nature and it decreases down the group.
(c) The no. 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 configurations of the elements are repeated in this manner.
(e) Advantages of the periodic table:
(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.