Intermolecular Forces Flashcards
Define dipole-dipole interaction
Attractive forces between very small dipoles in neighbouring POLAR molecules
Define intermolecular forces
Weak attractive forces between neighbouring molecules
How does v der w work
Movement of electrons
Disrupt distribution of charge
Instantaneous dipole formed
Induces a dipole on neighbouring molecule
Define v de w’s forces
Attractive forces between INDUCED DIPOLES in neighbouring molecules
Define electro negativity
The measure of attraction in a bonded atom for the pair of electrons in a covalent bond
Define a permanent dipole
A small charge difference across a bond resulting from a difference in electronegativities in a bonded atom
How do V de W increase
Increased no of electrons
Increased induced dipoles
Greater attractive forces between molecules
Hydrogen bonding
A STRONG DIPOLE INTERACTION between an electron deficient atom in one molecule
Abd a highly electronegative atom in another molecule
Properties of water
More dense than ice
High surface tension
High viscosity
Why does the boiling point increase from sodium to aluminium
Across the charge increases
The number of delocalised electrons increase
The electronegativities increase
The strength of metallic bond increases
Solubility of metallic ionic a covalent
Ionic- soluble in polar subs
Cov- insoluble in everything
Metallic - not
BP of cov ionic and metallic
C- simple molecular- weak v de w
Giant lattice- high
Ionic- high- strong electrostatic attraction
Metallic- high to dislodge ions from rigid positions
Define electronegativity
The measure of attraction of a bonded atom for the pair of electrons in a covalent bond
Why is BF3 non-polar and PF3 polar
BF3 is a symmetrical trigonal planar shape, the dipoles cancel out, whereas PF3, polar bonds, and an unsymmetrical pyramidal shape
How can you tell if the bonding is ionic or covalent based on electronegativites
The greater the difference between electronegativities, the more ionic the bond, the lower the difference the more covalent.
