Question

Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electron shells but different number of electrons in their outermost shells. It was found that elements A and G combine to form an ionic compound. This ionic compound is added in a small amount to almost all vegetables and dishes during cooking. Oxides of elements A and B are basis in nature while those of elements E and F acidic. The oxide of element D is, however, almost neutral. Based on the above information, answer the following questions:

(a) To which group or period of the periodic table do these elements belong?
(b) What would be the nature of compound formed by a combination of elements B and F?
(c) Which two of these elements could definitely be metals?
(d) Which one of the eight elements is most likely to be found in gaseous state at room temperature?
(e) If the number of electrons in the outermost shell of elements C and G be 3 and 7 respectively, write formula of the compound formed by the combination of C and G.

Answer 1

(a) The elements belong to the third period of the periodic table, and have the same number of electron shells but different number of electrons in their outermost shells. The number of valence electrons in these elements increases from 1 to 8, on moving from left to right in this period.

(b) When metal B combines with a non-metal F, an ionic compound is formed due to the transfer of electrons from the metal to the non-metal. This is because in the third period, elements A, B and C are metals, D is a metalliod, and E, F, G and H are non-metals.

(c) A and B are definitely metals because in the 3^rd period, at the extreme left, only metals are placed in the periodic table .

(d) The element H is most likely to be found in a gaseous state at room temperature. This is because the last group elements in the periodic table are all in a gaseous state at room tempearture.

(e) If the number of valence electrons of element C is 3 and those of element G is 7, then 1 atom of element C will combine with 3 atoms of element G to form a compound with the formula CG₃.