Physical Properties Related to Bonding TypeThe following is “sort of” a review of the properties for

the different kinds of bonding

Categorize by type of bonding

Ionic bonding held tight by strong electrostatic

forces in between cations and anions non-volatile, high mp, high bp solid at room temp hard and brittle because of a 3-D

lattice/crystalline structure conductivity

› non-mobile e- as solid = no› ions move freely when melted = yes› cations and ions separate when dissolved

in water = yes soluble in polar solvents like water

Covalent strong intramolecular forces, weak

intermolecular forces, usually liquids or gases at room temp or soft solid› strength of polarity and strength of

London forces determine mp and bp greater polarity = higher mp and bp greater van der Waals’ = higher mp and bp

often dissolve in nonpolar solvents but not in strong polar solvents like water

do not conduct electricity

Metallic high mp and bp

› decreases going down the periodic table harder for cations to attract the sea of

electrons› increases going across the periodic table

atomic radii becomes smaller, easier to attract the sea of electrons

low volatility not soluble in most solvents (polar or

non-polar) conduct electricity well because of

moving sea of electrons

Categorized by physical properties

Melting , Boiling, and Volatility

from highest to lowest1. metallic bonds 2. ionic bonds (cations and anions)4. hydrogen bonding (strong δ+ or δ-)

very strong when H is bonded with NOF (nitrogen, oxygen, or fluorine)

5. dipole - dipole *δ+ or δ-)6. London forces (weak, temporary δ+ or δ-)

For covalently bonded molecules generally speaking

› the greater the intermolecular force (IMF) between the molecules, the higher the melting point, boiling point, and volatility (evaporate) more electrons help increase the van der

Waals’ forces and keep the substance in the liquid state

molecules that can stick together better remain a liquid at higher temps.

boiling point increases

this flat shape allows it to stick to one another

better

these round shapes do NOT allow

them to stick to one

another

hydrogen bonding can occur here which is the

strongest type of dipole : dipole

intermolecular force

only normal dipole : dipole bonding can take

place

ethanol - higher BP dimethyl ether - lower BP

Exampe: two Lewis structures for the formula C2H6O. Compare the boiling points

of the two molecules.

Solubility “like dissolves like”

› polar substances tend to dissolve in polar solvents (ex. water dissolves ionic compounds) dissociation of salt YouTube (:53)

› non-polar substances tend to dissolve in non-polar solvents (ex. alcohol dissolves covalent molecules)

+

–+ +

–+

+

–+

+

–+ +

–+

+

–+

+

–+

+ –

+

+

–+

The dipoles of water attract, pushing the oil (with no partial charge) out of the

way: attractions win out over the

tendency toward randomness.

Conductivity substances must possess Freely Moving

Charged Particles› this occurs in…

metals with their “sea of electrons” YouTube (1:05)

molten ionic compounds (+ and – ions can move) http://www.dynamicscience.com.au/tester/solutions/

chemistry/bonding/bonding5.htm ionic compounds in aqueous solution

(dissolved in water) water pulls apart + and – ions and allows them to

move

Type of Bonding

Melting

Point

Boiling Point

Volatility

Electrical Conductivity

Solubility in Non-

polar Solvent

Solubility in Polar

Solvent

Non-polar

Low Low High No Yes No

Polar varies varies varies No No Yes

Hydrogen

bonding

varies varies varies No No Yes

Ionic Bonding

high high low Yes (molten or aqueous)

No Yes (most)

Metallic Bonding

high high low Yes No No

Covalent

varies varies varies No No No