Intermolecular Forces Flashcards
What does intermolecular bonding only apply to
Simple covalent bonds
What happends when there is a changing of state of matter for molecules
Bonds dont break intermolecular forces do
Define electronegativity
Measure of how strongly an atom attracts a pair of electrons in a covalent bond
What is the polarity of covalent bonds
Non polar
Define polarity
A polar covalent bond js one which the electron pair is unequally shared between the 2 atoms
E.g diagram of dipole moment
H 5+———-cl 5-
What do intermolecular forces only occur between
Van der walls- all molecules (weak)
Permanent diople-diople- polar (med)
Hydrogen bonding- specific polar
(Strong)
How do van der walls occur
Electrons move which creates a temporary diople inducing another dipole in another molecule which means there is very little energy required to overcome them
Name 1 thing that affects VDW forces
Size of molecule
Explain dipole-dipole forces
Strong electrostatic forces that exist between polar molecules
Weaker than ionic bonds they require a sig. Amount of energy to break them (> mp)
Common the of intermolecular force
What are the 2 exceptions to dipole-dipole
1) carbon hydrogen bonds (no difference in electronegativity)
2) molecule is symmetrical dipole-dipole cancel out
How do hydrogen bonds occur
Hydrogen bonds to either ( fluorine oxygen or nitrogen as they are the most electronegative)
Polar bond is created which is incredibly strong as mp is raised by 100 degrees
How do you work out which force has occured
Does the molecule contain F-H O-H N-H bond
/ /
Yes No
/ /
Hydrogen C-H BOND/ SY
Bond MMETRICAL
/ /
YES- VDW NO DIP-DIP
