Questions on Chemical Bonding

Chapter 6 - Answer Key to Section Review 1-3

Section Review 1

1. What is the main distinction between ionic and covalent bonding?

Answer (A): Ionic bonding involves the electrical attraction between large numbers of anions and cations. Covalent bonding involves the sharing of electron pairs between two atoms.

Translation:

-Ionic bonding happens between a metal and a non-metal (east coast and west coast)

-One atom completely donates its valence electrons to another atom

-Metals become CATIONS (positive charge/oxidation state); Non-metals become ANIONS (negative charge/oxidation state)

Example: Na + Cl → Na+Cl- or Mg + O → Mg2+O2-

-In covalent bonding one atom completely shares its valence electrons with another atom (west coast and west coast)

Example: H2O, CO2

2. How is electronegativity used in determining the ionic or covalent character of the bonding between two elements?

A: A large difference in electronegativity between two atoms in a bond will result in ionic bonding. A small difference in electronegativity between two atoms will result in covalent bonding.

Translation: Electronegativity difference between 0-0.3 = Non-polar covalent bond

Electronegativity difference between 0.3-1.7 = Polar covalent bond

Electronegativity difference greater than 1.7 = Ionic bond

3. What type of bonding would be expected between the following atoms?

a) Li and F = ionic
b) Cu and S = polar-covalent
c) I and Br = polar-covalent
Translation:

Non-polar covalent bond – the electron pairs that make up the bond are “hanging out” right in the middle of the two atoms

Polar covalent bond – the electron pairs that make up the bond are “hanging out” closer to the more electronegative atom

4. List the three pairs of atoms referred to in the previous question in order of increasing ionic character of the bonding between them.

A: I and Br, Cu and S, Li and F

5. Compare the following pairs of atoms: Cu and Cl;