Date post: | 01-Jan-2016 |
Category: |
Documents |
Upload: | imogene-waters |
View: | 217 times |
Download: | 0 times |
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 ____________.