Question

(a) Write the symbols/formulae of two simple ions and two compound ions (or polyatomic ions).
(b) An element Y has a valency of 4. Write the formula for its :
(i) chloride
(ii) oxide
(iii) sulphate
(iv) carbonate
(v) nitrate

Answer 1

(a) Example of a simple ion: Iodine atom forms an iodide ion by accepting an electron, I^-. Similarly, magnesium loses two electrons to form a magnesium ion, Mg²⁺.
Example of a compound ion: Carbonate ion, CO₃^2-, is made up of two types of atoms i.e. carbon and oxygen (chemically bonded). Similarly, ammonium ion, NH₄⁺, is made up of two types of atoms i.e. nitrogen and hydrogen (chemically bonded).

(b) Formula for the listed compounds are as follows:
(i) Crossing the valencies, chloride for the element Y will have the chemical formula YCl₄.


(ii) Crossing over the valencies, oxide for the element Y will have the chemical formula YO₂.


(iii) Crossing the valencies, sulphate for the element Y will have the chemical formula Y(SO₄)₂.


(iv) Crossing the valencies, carbonate for the element Y will have the chemical formula Y(CO₃)₂.


(v)Crossing the valencies, nitrate for the element Y will have the chemical formula Y(NO₃)₄.