Question

1. How is an ionic bond formed?

2. Given its formula ONLY, how can you determine if a compound is molecular (covalent) or electrovalent (ionic)? Use a minimum of two examples to explain.

3. Name or write the formula: a). P4O7 b). copper(II) oxalate c). chlorous acid d). triselenium hexaiodide e). H2CO3 f). V3(PO3)5

Answer 1

1. When transfer of electron takes place between metal and non-metal, ionic bond forms. For example, an electron is removed from Na-atom to form Na⁺ and Cl-atom accept that electron to form Cl^--ion and the compound formed is NaCl. due to to electrostatic force of attraction between cation (Na⁺) and anion (Cl^-). Ionic bond strength depends on the difference in electronegativity of cation and anion.

2. Ionic bond forms between a metal and non-metal while covalent bond forms between two non-metals. So, if we have knowledge about metal and non-metals of the periodic table, we can guess the nature of bond. Second method is to find the electronegativity difference and if this difference comes between 0-1.7 (or 1.9), the bond is covalent and if the diiference comes above 1.7 (or 1.9), the bond is ionic.

Examples; a) NaCl: Na is metal and Cl is non-metal. Also the electronegativity difference is 3-0.9 = 2.1> 1.7 So, the bond is ionic.

b) Cl₂: Both are non-metal and E.N difference is 3-3=0. So, Cl₂ is covalent molecule

c) HCl: H is non-metal and Cl is also nonmetal and E.N difference is 3-2.2=0.8<1.7 So, the compound is Covakent in nature.

3.

a) P₄O₇ : Tetra phosphorus heptoxide

b) Copper (II) oxalate: CuC₂O₄

c) Chlorous acid: HClO₂

d) triselenium hexaiodide: Se₃I₆

e) H₂CO₃: Carbonic acid

f) V₃(PO₃)5 :Vanadium(v) Phosphite

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