The position of three elements A, B and C in the Periodic Table are shown below:
The position of three elements A, B and C in the Periodic Table are shown below:
| Group 16 | Group 17 |
|
- - - B |
-
A - C |
(i) State whether A is a metal or a non-metal.
(ii) State whether C is more reactive or less reactive than A.
(iii) Will C be larger or smaller in size than B?
(iv) Which type of ion—cation or anion will be formed by element A?
4 Answers
(i) Metals lie on the left-hand side of the Periodic table whereas non-metals are found on the right-hand side. The element A is in group 17. Group 17 is on the right side of the Periodic table. Thus, element A is a nonmetal
(called halogen).
(ii) The chemical reactivity of non-metals decreases on going down in a group. In group 17, the chemical reactivity decreases on going down in a group. So, element C is less reactive than A.
(iii) The atomic size decreases in moving from left to right along a period. So, atom C will be smaller in size than B.
(iv) The element A of group 17 has 7 valence electrons. So, it will gain one electron to form a negatively charged ion (A–). The negatively charged ion is called an anion. So, element A will form an anion.
(a) A is a non-metal because it can gain electrons easily, it has 7 valence electrons and form negative ions to become stable.
(b) The atomic number of B is less than C, it has less nuclear charge, less force of attraction between protons in the nucleus and valence electrons, hence its size is bigger than C.
(c) Element ‘C’ has 7 valence electrons, it can gain 1 electron to become stable so its valency is 1.
(a) ‘A’ is a metal because its valence electron is 1, it can readily loose electron to became stable.
(b) Element ‘C’ belongs to 3rd period it has 3 shells whereas ‘B’ has only 2 shells, it belongs to 2nd period, distance between nucleus and valence electrons is more in C, hence its size is bigger than B.
(c) ‘B’ belongs to III group, has 3 valence electrons, it can loose 3 electrons to become stable hence its valency is 3.
(a) A is a non-metal because it can gain electrons easily, it has 7 valence electrons and forms negative ions to become stable.
(b) The atomic number of B is less than C, it has less nuclear charge, less force of attraction between protons in the nucleus and valence electrons, hence its size is bigger than C.
(c) Element ‘C’ has 7 valence electrons, it can gain 1 electron to become stable so its valency is 1.