Bonding and structure: key terms
8 terms. Say the definition out loud, tap to check, then say whether you knew it. Back to the topic
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Ionic bonding
The electrostatic attraction between positive and negative ions.
Examiners say "Electrostatic attraction" and "oppositely charged ions" are the marks. Do not mention sharing or molecules.
Covalent bond
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
Examiners say Both parts are needed: shared pair, and attraction to both nuclei.
Dative covalent bond
A covalent bond in which both electrons of the shared pair come from one of the bonded atoms.
Examiners say Also called a coordinate bond. Show it as an arrow from the atom that donates the pair.
Electronegativity
The ability of an atom to attract the bonding electrons in a covalent bond.
Examiners say It increases across a period and up a group; fluorine is the most electronegative element.
Polar bond
A covalent bond between atoms of different electronegativity, giving a permanent dipole with δ+ and δ− ends.
Examiners say A molecule with polar bonds is non-polar overall if it is symmetrical and the dipoles cancel.
Hydrogen bond
A strong permanent dipole–dipole attraction between an electron-deficient hydrogen atom bonded to N, O or F and a lone pair on a N, O or F atom of another molecule.
Examiners say In a diagram show the lone pair, the dipoles, and the hydrogen bond as a dashed line to the lone pair.
London forces
Induced dipole–dipole interactions, present between all molecules, which increase with the number of electrons.
Examiners say Explain in three steps: electrons move, giving an instantaneous dipole; this induces a dipole in a neighbouring molecule; the dipoles attract.
Electron-pair repulsion
Electron pairs around a central atom repel one another and get as far apart as possible; lone pairs repel more than bonded pairs.
Examiners say State the number of bonded pairs and lone pairs, then the shape and angle. Each lone pair reduces the bond angle by about 2.5°.
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