question_answer 17)

                (a) What property do all electrons in the same column of the periodic table as boron have in common ? (b) What property do all elements in the same column of the periodic table as fluorine have in common ?                  

Answer:

(a)All the elements which lie in me same column as that of boron belong to group 13. Therefore, they have three electrons in their respective valence shells. Except, boron which is a non-metal, all other elements (i.e., aluminium, gallium, indium and thallium) in this group are metals. (b) The elements which lie in the same column as fluorine are called halogens. They belong to group 17 and thus have seven electrons in the valence shell. Therefore, their valency is 18 -17 = 1. All these elements (fluorine, chlorine, bromine, iodine and astatine) are non-metals.