Oxygen gas is made of O2\mathrm{O_{2}}O2 molecules, in which two oxygen atoms are held together by covalent bonding.
How many outer-shell electrons in one O2\mathrm{O_{2}}O2 molecule are not shared, and how many electrons are shared between the two atoms?
10 electrons not shared, 2 electrons shared
4 electrons not shared, 8 electrons shared
8 electrons not shared, 4 electrons shared
4 electrons not shared, 4 electrons shared
122 exam-style questions on OCR GCSE Chemistry 2.2 Bonding, covering 2.2.1 Metals, non-metals and the Periodic Table, 2.2.2 Types of chemical bonding and dot and cross diagrams, 2.2.3 Limitations of bonding models, and 2.2.4 Reactivity, atomic number and the modern Periodic Table. Each one has a worked solution and a mark scheme showing where the marks go.