Q26 of 30 Page 196

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?

(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.


More from this chapter

All 30 →
24

An element has electronic configuration 2, 8, 7.

(a) To which group and period of the long form of Periodic Table does it belong?


(b) What is atomic number of this element?


(c) Is it metallic or non-metallic and why?


(d) Identify the element.


(e) Name an element chemically similar to this element.

 25

The positions of three elements A, B and C in the periodic table are indicated below:


(a) State whether element C would be a metal or a non-metal. Why?


(b) Which is the more active element, A or C? Why?


(c) Which type of ion (cation or anion) will be formed by the element C? Why?

 27

In the following table, six elements A, B, C, D, E and F (here letters are not the usual symbols of the elements) of the modern Periodic Table with atomic numbers 3 to 18 are given:


(a) Which of these is (i) a noble gas, (ii) a halogen?


(b) If B combines with F, what would be the formula of the compound formed?


(c) Write the electronic configurations of C and E.

 28

In the following table, are given eight elements A, B, C, D, E, F, G and H (here letters are not the usual symbols of the elements) of the Modern Periodic Table with the atomic numbers of the elements in parenthesis.


(i) What is the electronic configuration of F?


(ii) What is the number of valence electrons in the atom of F?


(iii) What is the number of shells in the atom of F?


(iv) Write the size of the atoms of E, F, G and H in decreasing order.


(v) State whether F is a metal or a non-metal.


(vi) Out of the three elements B, E and F, which one has the biggest atomic size?