What intermolecular forces are present in CH_4?
Just London (dispersion forces).Because methane is a non-polar molecule it
is not capable of hydrogen bonding or dipole-dipole intermolecular
forces.
The only intermolecular forces in methane are London dispersion
forces.The major intermolecular forces would be dipole-dipole forces and
London dispersion forces.The electronegativities of C and H are so close
that C-H bonds are nonpolar. There are no bond dipoles and no dipole-dipole
interactions.Even if the molecule had polar C-H bonds, the symmetry of
molecule would cause the bond dipoles to cancel. The molecule would still
be nonpolar. It is a blob with no positive or negative
ends.Virtual ChemBook only
forces left to consider are London dispersion forces.In a nonpolar
molecule, electrons are always moving. At any instant, they might be at one
end of the molecule. This would instantaneously create a temporary dipole,
making that end negative and the other end
positive.
positive charge attracts the electrons in an adjacent molecule. This
temporary attractive force is the London dispersion forceThe
London dispersion forces are so weak that methane does not condense to a
liquid until it cools to −161.5 °C.
