Intermolecular Foces Flashcards
What is the relative strength of Van der waals
1
What is the relative strength of Permanent dipole-dipole interactions
50
What is the relative strength of Hydrogen bonds
50
What is the relative strength of ionic & covalent bonds
1000
How does an induced dipole interactions (London forces) form?
Fluctuations in the electron density around a molecule creates an instantaneous dipole in a molecule. The instantaneous dipole induces a dipole in the neighbouring molecules which then attract one another causing weak intermolecular forces
Definition of permanent dipole-dipole interactions
its a weak attractive forces between permanent dipole and permanent dipole in different polar molecules
Definition of Van der Waals
they are attractive force between induced dipoles in neighbouring molecules
Definition of hydrogen bonding
its a strong permanent dipole - permanent dipole attraction between molecules :
> Containing N, O or F and the H atom of –NH, –OH or HF
> and a lone pair of electron on a highly electronegative atom (O, N, or F) on a different molecule
Why is ice less dense than water?
ice has an open lattice with hydrogen bonds holding the water molecules aparts
Why does water have higher melting and boiling point than expected
because there are relatively strong hydrogen bonds between H2O molecules which are much stronger than other intermolecular forces
