IB Chemistry SL 2.2.1 Covalent Bonding Questions

Use exam questions to describe shared-electron covalent bonds, count valence electrons and draw octet-respecting Lewis formulas.

Exam points

Describe a covalent bond as electrostatic attraction between a shared electron pair and the positively charged nuclei of the bonded atoms.
Count valence electrons before placing bonding pairs, lone pairs and any overall ionic charge in a Lewis representation.
Draw a Lewis formula with single, double or triple bonds and lone pairs so each relevant atom reaches the octet rule (or the stated incomplete-octet exception).

[Maximum number: 1]

Ethyne, $\mathrm{C}_{2} \mathrm{H}_{2}$ , reacts with oxygen in welding torches.

Deduce the Lewis (electron dot) structure of ethyne.

$\mathrm{H}: \mathrm{C}:: \mathrm{C}: \mathrm{H} / \mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}$

Marking guidance:

Accept any valid combination of lines, dots and crosses.

All question bank results loaded