Bonding

Physical Properties of Metals

I. ______________________II. ______________________III. __________________________IV. Malleable: __________________________V. Ductile: ___________________________

How are these different than ionic crystals?

Electron Sea Model for Metallic Bonding

A. Array of metal cations in a ________ of _______________ electrons.

B. Electrons are mobile, no individual electron is confined to a particular cation.

C. Free electron flow = _________ electrical conductivity toward + from –

D. High ________ conductivity: mobile electrons transfer ______________________ throughout the solid

E. ______________ are connected to many electrons, easily changed, redistributed (malleable and ductile)

F. Weakness of model: doesn’t adequately explain melting point, boiling point, hardness or heat of fusion.

Na Cl

Types of Crystals

_______________• Lattice points occupied by _________ and ____________• Held together by _____________________ attraction• __________________________________• ___________ conductor of heat and electricity

(____________)

CsCl ZnS CaF2

Physical Properties and Bonding Type

Bond Type

Ex Electron Placement

Structu-ral Unit of Solid

Intermolecular Forces

Melting Point

Boiling Point

Viscosity Solubility Volatility Condu-ctivity

Ionic NaCl Na+ Cl-

Transfer e-

Ion Ionic Lattice

Strong attraction (usually solid)

Very high 800˚C

Very high!

None in solid

Very soluble in polar solvent(NaCl in H2O)

No in aq, lnot solid

Polar Covalent

H2O H - O- H

Unequalsharing

Molecule Dipole-dipole

H-Bonding

(usually liquid)

Medium0˚C

increase with IMF

Medium100˚C

Yes, increases with temp

Very soluble in polar solvent

Some, increases with temp

None

Non-polar Covalent

CH4

I2

(Gr 18)

HH- C- H H

Equally sharing

Molecule

Atom

Van der Waal forces London Dispersion(usually a gas)

Very low

Increasewith mass size

Increases with size

-162˚C

Low-runs fast

In nonpolar solvent only

Yes- except with increasing mass

No

Metallic CuAgFe

Sea of electrons

Atom Strong Malleableductile

Wide range

Wide range

no Depends on chemical reaction with solvent

NO Yes-very

Intermolecular Forces• ___________ than covalent bonds• Interactions are __________________

molecules, __________________.• Molecules remain ________________

during phase changes, only the _______________ between molecules change.

• These are what hold the molecules together in the condensed states.

Generally, intermolecular forces are much weaker than intramolecular forces.

Types of intermolecular forces

• _______________________

• _______________________

• __________________________________

“Measure” of intermolecular force

_____________ Attractions

• Between __________ molecules (CH3COCH3)

• Polar molecules have ________________ and _____________________ charged regions.

• Molecules orient themselves to ________________ repulsion and maximize attraction.

• Only 1% as strong as covalent or ionic bonds• Rapidly _____________________ with distance, no effect

in gases.

+- +-

+-

+

-+

-

+-

+-+-

+-

+-

____________ Bonding

• Specialized ________________ interaction

• H-X where X is very electronegative and very small. (i.e. H2O, NH3, HF)

• _____________ boiling point greatly• Especially ___________ dipole-dipole

forces when H is attached to ____________

Water

+-

+

Boiling Points

Compound Formula Mol. Wt. Boiling Point Melting Point

dimethyl ether CH3OCH3 46 –24ºC –138ºC

ethanol CH3CH2OH 46 78ºC –130ºC

propanol CH3(CH2)2OH 60 98ºC –127ºC

diethyl ether (CH3CH2)2O 74 34ºC –116ºC

propyl amine CH3(CH2)2NH2 59 48ºC –83ºC

methylaminoethane CH3CH2NHCH3 59 37ºC  

trimethylamine (CH3)3N 59 3ºC –117ºC

ethylene glycol HOCH2CH2OH 62 197ºC –13ºC

acetic acid CH3CO2H 60 118ºC 17ºC

ethylene diamine H2NCH2CH2NH2 60 118ºC 8.5ºC

_____________________• All substances exert _________________ on

each other, thus they can be solids and liquids.• Electrons can __________ around the nucleus to

create a _______________ dipole.• This _________________ a dipole in the

neighboring molecule• _____ nonpolar molecules are noble gases exert

VdW forces. ________________________• The ___________ the molecule, the

_____________ the forces between the molecules.

Example

H H H HH H H H

+ +

H H H H

+ - +

What type(s) of intermolecular forces exist between each of the following molecules?

HBr

CH4

SO2

Summary

• A _____________ bond between two different atoms is a polar covalent bond.

• The electronegativity of an atom is a measure of its _______________________________.

• Electron density in a covalent bond is skewed towards that of __________ electronegativity.

• The atom of ____________ electronegativity has a partial negative charge _____.

• The atom of __________ electronegativity has a partial positive charge ________.

• ___________ covalent bonds result from the _____________ sharing of bonding pairs of electrons in covalent molecules.

• Overall, a polar molecule has two oppositely charged regions: acts like a ____________.