atoms joined by strong covalent bonds insoluble in all solvents (polar or non-polar) high mp and...
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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
Giant Network Covalent – carbon allotropes and silicon
atoms joined by strong covalent bonds insoluble in all solvents (polar or non-
polar) high mp and bp e- firmly held in place therefore no
conductivity› exception is graphite and graphene that
have moving electrons
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
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. macromolecular (giant) covalent molecules
very strong intermolecular forces hold molecules together
diamonds, silicon dioxide, graphite (boils at 4830°C)
2. metallic bonds 3. 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)
giant network covalent molecules and metals do not dissolve in most solvents
+
–+ +
–+
+
–+
+
–+ +
–+
+
–+
+
–+
+ –
+
+
–+
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 graphite (delocalized electrons move
between the layers)
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
Giant Covalen
t
High High Low No (except graphite and
graphene)
No No
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