Covalent Bonding — Drills · Grade 11 Science

Chapter: Bonding, Formulas & Molecular Structure

What these drills covers

By the end of Covalent Bonding you should be able to:

6 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: covalent bond, molecule, bonding pair, lone pair, Lewis structure, double bond, triple bond, diatomic molecule.

Problem 1

A shared pair of electrons that forms a bond is called a…
  1. lone pair
  2. bonding pair
  3. cation
  4. lattice
Answer and explanation

bonding pair

A pair of electrons shared between two atoms is a bonding pair.

Problem 2

How many electrons are in a single covalent bond?
Answer and explanation

2

A single bond is one shared pair, which is 2 electrons.

Problem 3

A molecule of N₂ has a triple bond. How many shared (bonding) electrons are between the two atoms?
Answer and explanation

6

A triple bond is 3 shared pairs, and 3 × 2 = 6 electrons.

Problem 4

Which is a typical property of a molecular (covalent) compound?
  1. a very high melting point
  2. conducts electricity as a solid
  3. a low melting point and poor conductivity
  4. it is made of ions in a lattice
Answer and explanation

a low melting point and poor conductivity

Weak attractions between molecules give low melting points, and locked-up electrons mean poor conductivity.

Problem 5

Explain the difference between a bonding pair and a lone pair of electrons.
Answer and explanation

A bonding pair is a pair of electrons shared between two atoms, forming a covalent bond. A lone pair is a pair of valence electrons on a single atom that is not shared and does not form a bond.

Problem 6

In the Lewis structure of a water molecule (H₂O), how many lone pairs are on the central oxygen atom?
  1. 4
  2. 0
  3. 1
  4. 2
Answer and explanation

2

Oxygen has 6 valence electrons; 2 are used in the two O–H bonds, leaving 4 electrons — that is 2 lone pairs.

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