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CHAPTER 5 • 6 MARKS

Ionic and Covalent Bonding

Understand electron transfer, electron sharing, Lewis structures and properties of ionic and covalent compounds.

Topics in this chapter

  1. Valence electrons and octet rule
  2. Electrovalency
  3. Formation of cations and anions
  4. Ionic bond formation
  5. Covalency
  6. Single, double and triple bonds
  7. Lewis electron-dot structures
  8. Properties of ionic compounds
  9. Properties of covalent compounds

Key learning points

✓ Ionic bonds form through electrostatic attraction after electron transfer.

✓ Covalent bonds form by sharing electron pairs.

✓ Ionic compounds usually conduct electricity in molten or aqueous states.

✓ Most covalent compounds have relatively low melting and boiling points.

Important equations and relations

Na → Na⁺ + e⁻Cl + e⁻ → Cl⁻Na⁺ + Cl⁻ → NaClH· + ·H → H:H

Multiple-choice questions

1. A covalent bond is formed by:
  1. Transfer of protons
  2. Sharing of electrons
  3. Transfer of neutrons
  4. Loss of nuclei

Answer: B — Sharing of electrons

2. Which is mainly ionic?
  1. CH₄
  2. H₂
  3. NaCl
  4. Cl₂

Answer: C — NaCl

3. Molten ionic compounds conduct because they contain:
  1. Free atoms
  2. Mobile ions
  3. Free neutrons
  4. Only molecules

Answer: B — Mobile ions

Very short-answer questions

  1. Define electrovalency.
  2. What is a covalent bond?
  3. Draw the electron-dot structure of H₂.

Short-answer questions

  1. Explain formation of NaCl by electron transfer.
  2. Compare physical properties of ionic and covalent compounds.

Long-answer question

  1. Describe ionic and covalent bond formation with suitable electron-dot structures.