Chemistry Bonding
The electron pair repulsion theory states that the electron pairs in the valence energy level of an atom repel each other, and therefore are arranged as far apart as possible. For example, H2O:Due to this theory, different molecules with different amounts of pairs of electrons have different shapes. Some common shapes of molecules include linear, trigonal planar, tetrahedral, trigonal pyramidal and v-shaped (bent) molecules. Examples are drawn below-a) linear (CO2) The electron dot diagrams must be drawn first in order to work out the shape of the molecule.The polarity can be determined from the shape of the molecule. In essence, a molecule is polar if there is an overall electro
So, to predict the type of intermolecular forces shown in a particular substance, determine whether it is polar or non-polar, and then whether it exhibits hydrogen bonding. Using these rules, we can determine the polarity of the earlier used examples. If a molecule is of the form AB3 and is trigonal planar, it is non-polarIf a molecule is of the form AB4 and is tetrahedral, it is non-polar. Polar molecules exhibit dipole-dipole intermolecular forces, and the strength of this force is increased with a greater electronegativity difference between atoms in the molecule. Non-polar molecules exhibit dispersion forces, and these are very weak. This can be determined using some basic rules, which state that:If a molecule is of the form AB2 and is linear, it is non-polar. We can do this for the examples introduced earlier. a) AB2 Ö b) AB4 Ö c) AB2 Ö d) AB3 Ö e) AB3 Ö linear Ö tetrahedral Ö bent X trigonal planar Ö trigonal pyramidal Ö non-polar non-polar polar non-polar polarIntermolecular Forces:As we have just seen, it is easy to determine the molecular polarity of a particular molecule after seeing the shape. Knowing the polarity and the nature of the molecule, we can then work out the type and strength of intermolecular force in the substance. Hydrogen bonding is the strongest form of intermolecular force and occurs only between H and O, N or F. a) dispersion forces b) dispersion forces c) dipole-dipole forces (hydrogen bonding) d) dispersion forces e) dipole-dipole forces (hydrogen bonding)Therefore, we can see that the three dimensional structure of a covalent molecule can be used to predict molecular polarity and intermolecular forces in that substance, thus proving that the shape is an important property of any molecule. negativity difference in the molecule. The higher the molecular mass of the substance, the stronger the dispersion forces because in the larger molecule, electrons are more likely to be influenced by external forces that cause the distribution of electrons in the molecule to suddenly become uneven. The last type of intermolecular forces shown is a sub-division of dipole-dipole bonding, and that is hydrogen bonding.
Common topics in this essay:
Intermolecular Forces,
Molecular Polarity,
Shapes Molecules,
Repulsion Theory,
H2O Due,
dispersion forces,
hydrogen bonding,
intermolecular forces,
trigonal planar,
molecule form,
trigonal pyramidal,
molecular polarity,
forces dipole-dipole forces,
bonding hydrogen bonding,
dipole-dipole forces hydrogen,
forces shown,
bonding hydrogen,
type intermolecular,
forces hydrogen bonding,
intermolecular forces shown,
|
Acceptance Essays
