CAIE A Level Chemistry 9701 · Chemical bonding
Two oxygen atoms in a molecule of are joined by a covalent bond. A student draws a dot-and-cross diagram of , using dots for the outer-shell electrons of one atom and crosses for the outer-shell electrons of the other.
Suggest what the diagram shows about the electrons in the molecule, and explain how it shows that each oxygen atom has a noble-gas electron configuration.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Suggest means: Apply what you know to an unfamiliar situation. There may be more than one acceptable answer. Reason from the principle you have learned to the new context, and say which principle you are using.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.