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What can you recall?
state / explain / deduce / identify / name
Recall and explain
(a) State what a covalent bond is. Hydrogen bromide, HBr, is made of molecules; a bromine atom has 7 outer electrons. Explain why a hydrogen atom and a bromine atom share one pair of electrons, not two. (b) Supplement: in a molecule X2, the two atoms share two pairs of electrons and each atom keeps two lone pairs. Deduce how many outer electrons an atom of X has, identify X from carbon, nitrogen, oxygen and fluorine, and name the type of bond.
state: give a concise answer. explain: give reasons and connect them to evidence. deduce: reach a conclusion from the information given. identify: name or select. name: use the given information.
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Scope and sources
Cambridge IGCSE Chemistry 0620 · 2026–2028 v2 · Original learning materials.
Simple molecules and covalent bonds (2.5 Core 1–3, Supplement 4–5): the covalent bond as a shared pair of electrons that gives noble-gas electronic configurations, dot-and-cross diagrams for H₂, Cl₂, H₂O, CH₄, NH₃ and HCl and, in the Supplement, CH₃OH, C₂H₄, O₂, CO₂ and N₂, and the low melting and boiling points and poor electrical conductivity of simple molecular compounds, explained in the Supplement by weak intermolecular forces and no moving charged particles. Giant covalent structures (2.6), metallic bonding (2.7) and formulae (3.1) have their own modules; the shapes of molecules are not in the syllabus.
Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.
Official Cambridge syllabus