Unit 8: intermolecular forces Flashcards
1
Q
What are intra-molecular forces?
A
- Interactions of atoms within a molecule
- Can be metallic, ionic or covalent
- Stronger than intermolecular forces
2
Q
What are inter-molecular forces?
A
- Interactions between molecules, atoms or ions, so between chemical species
- Affect physical propreties, such as boiling and melting point
- State of matter depends on the magnitude of intermolecular forces (Liquids and solids = strong and gases = weak)
3
Q
What are metallic bondings?
A
- Between metallic atoms
- Valence electrons move freely through the structure
4
Q
London dispersion force (LDF)?
A
- Type of inter-molecular force (temporarily)
- All substances have LDF
- When electrons are temporarily unsymmetrically distributed in a molecule
- Results in short-lived dipole moments, that creates polarity in molecules, even in non-polar bonds
- Larger atoms/molecules are said to be polarized, because have more electrons
- Consequences: higher melting and boiling points that expected
5
Q
Dipole-dipole interactions?
A
- Type of inter-molecular force (permanent)
- Between polar molecules with net dipoles
- Permanent dipole due to uneven sharing of electrons
- Consequences: higher melting/boiling points than nonpolar molecules
6
Q
Hydrogen bonds?
A
- Strong dipole-dipole interaction
- O-H, N-H, F-H bonds are highly polarized
- Due to very small size of hydrogen atoms
7
Q
Ion-dipole forces?
A
- Electrostatic attractions between ions and polar molecules
- Ex: NaCl in water
- Most commonly found in solutions
- The strongest force