Secondary bonding Flashcards
asymmetrical molecule
a molecule in which the polar bonds are unevenly ( or asymmetrically) distributed.
The dipoles DO NOT cancel each other out, and an overall molecular dipole is produced.
dipole/ electric dipole
the separation of areas of positive and negative charge in a molecule.
dipole-dipole force
a form of intermolecular force that occurs between polar molecules where the partially positively charged end of one molecule is attracted to the partially negatively charged end of another molecule.
dispersion force
the force of attraction between molecules due to temporary dipoles induced in the molecules. The temporary dipoles are the result of fluctuations in the electron density.
electron density
the concentration of electrons that usually refer to the regions around an atom or molecule.
hydrogen bond
a type of intermolecular , dipole-dipole force where a hydrogen atom is covalently bonded to a highly electronegative atom such as F, N, O .
Due to the electronegativity differences, the hydrogen develops a partial positive charge that can bond with the electron pair of the neighbouring O,F, O.
e.g. water, ammonia, HF.
instantaneous dipole
a net dipole formed in a molecule due to temporary fluctuations in the electron density in the molecule.
non-polar
bonds or molecules that do not have a permanent dipole. They have an even distribution of charge.
polar
bonds or molecules with a permanent dipole. They have an uneven distribution of charge.
polarity
the measure of how polar a molecule or bond is.
The difference in charge between the positive and negative ends of an electric dipole, polar molecule or covalent bond.
surface tension
the resistance of a liquid to increase its surface area.
Force that holds the liquid together like a “skin”.
symmetrical molecule
a molecule in which the polar bonds are evenly (symmetrically) distributed.
The bond dipoles cancel out and do NOT create an overall molecular dipole.
temporary dipole
a net dipole formed in a molecule due to temporary fluctuations in the electron density in the moleule
VSEPR theory
Valence Shell Electron Pair Repulsion Theory
A model used to predict the shape of molecules..
Since e- repel each other, they will adopt an arrangement that minimizes this repulsion.
i.e. they move as far apart in 3D as possible.
vapour pressure
the pressure exerted by molecules that evaporate from a liquid in an enclosed vessel at the point where the rates of evaporation and condensation are in equilibrium
i.e. the molecules leave and re-enter the liquid at the same rate.
