Bonding & Structure Flashcards
Ionic bond
Strong electrostatic attraction between two oppositely charged ions. Strength of
attraction depends on the relative sizes and charges of ions.
Cation
A positively charged ion,
Anion
A negatively charged ion
Isoelectronic species
Chemical species that have the same number of electrons, e.g. N(3−), O(2−), F(−) ions
Covalent bond
The strong electrostatic attraction between two nuclei and the shared pair of
electrons between them.
𝞼 (sigma) bond
A bond that results from a direct (end-on) overlap of two orbitals
π (pi) bond
A bond that is formed when two orbitals overlap sideways,
Dative covalent bonding
Occurs when one atom donates both electrons in a bond. e.g. in NH4+ or H3O+ ions. Marked with an arrow.
Allotropes
Different forms of the same element, e.g. allotropes of carbon are: diamond, graphite,
graphene, fullerenes, carbon nanotube
Malleable
substance can be shaped.
Ductile
substance can be drawn into a wire.
Intermolecular forces
Forces between the molecules
Electronegativity
The ability of atom to attract the bonding electrons in a covalent bond
Dipole
Difference in charge between the two atoms of a covalent bond caused by a shift in electron
density in the bond due to the electronegativity difference between elements participating in
bonding
Metallic bonding
Strong electrostatic attraction between metal ions and the sea of delocalised
electrons that surround them.
Delocalised electron
The electrons that are not contained within a single atom or a covalent bond
Bond length
Internuclear distance between two covalently bonded atoms
London forces
Weak intermolecular forces arising due to fluctuations of electron density within a
nonpolar molecule. These fluctuations may temporarily cause the asymmetric electron distribution :
the molecule becomes an instantaneous dipole
Permanent dipole-dipole interactions
Dipole-dipole attractions between polar molecules. Stronger
than London forces.
Hydrogen bond
A type of intermolecular force (with some bonding character) between a hydrogen
bonded to a more electronegative atom than hydrogen (usually N,O,F) and other atom in a
same/different molecule. Directional nature - the bond angle is often 180°. Responsible for
anomalous properties of water, e.g. the density of ice < density of water. Ice occupies greater
volume than water due to the directional nature of hydrogen bonds within the solid structure.
