Question

Atoms of seven elements A, B, C, D, E, F and g have a different number of electronic shells but have the same number of electrons in their outermost shells. The elements A and C combine with chlorine to form and acid and common salt respectively. The oxide of element A is liquid at room temperature and is a neutral substance, while the oxide of the remaining six elements are basic in nature. Based on the above information, answer the following question: 

(i) What could the element A be? (ii) Will element A to G belong to the same period or same group of the periodic table? 

(iii) Write the formula of the compound formed by the reaction of the element A with oxygen. 

(iv) Show the formation of the compound by a combination of element C with chlorine with the help of electronic structure. 

(v) What would be the ratio of number of combining atoms in a compound formed by the combination of element A with carbon? (vi) Which one of the given elements is likely to have the smallest atomic radius?

Answer 1

(i) A will be hydrogen (H) because A, B, C, D, E, F and G all have same number of valence electrons so this means these elements belong to same group. Since element C combine to Cl and forms NaCl so these elements belong to 1 group. Only H form an acid on reaction with Cl in 1 group and its oxide is also neutral substance. 

(ii) Elements A to G will belong to same group but periods will different because number of shells are different in all elements. 

(iii) A is hydrogen (H) then the formula of the compound formed by the reaction of the element A with oxygen is H₂O. 

(iv) Element C is Na because C combine with chlorine and forms common salt (NaCl)

(v) A is H so the compound formed by the combination of element A with carbon will be CH₄ and the ratio of combining atoms will be 4:1. 

(vi) The element which has the smallest atomic radius is A.