AQA GCSE Chemistry · 8462
Specification 4.1.2.3 · Paper 1
Revise: Metals and Non-MetalsHydrogen is an important positional exception: it is placed above Group 1 because it has one outer-shell electron, but it is a non-metal.
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GCSE Chemistry · key term
The electrons in the highest occupied energy level of an atom; these are involved in chemical reactions.
Used by AQA and OCR
Specification 4.1.2.3 · Paper 1
Revise: Metals and Non-MetalsHydrogen is an important positional exception: it is placed above Group 1 because it has one outer-shell electron, but it is a non-metal.
Specification C2.2d · Paper 1 (Foundation), Paper 3 (Higher)
The electrons in an atom's highest occupied energy level, which take part in covalent bonding.
Revise: Simple Molecular SubstancesRather than transferring electrons and forming ions, they share outer-shell electrons. The nuclei remain unchanged during this process.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
Electrons in the highest occupied electron shell of an atom; these are the electrons shown in a dot and cross diagram.
Revise: Dot and cross diagrams for covalentAtoms of non-metal elements can bond by sharing outer-shell electrons. The shared electrons are attracted to the nuclei of both bonded atoms, producing a strong covalent bond. A dot and cross diagram is a model that shows these outer-shell electrons.
When explaining reactivity, link the element's atomic number to its electron arrangement, then focus on what happens to its outer-shell electrons.
Check the total number of outer-shell electrons: it must equal the sum contributed by all the atoms.
Put bonding pairs between the bonded atoms and include every unshared outer-shell electron as part of a lone pair.
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