文档介绍：Ice Physics
Sveinung Løset, prof.
Department of Civil and Transport Engineering,
Marine Civil Engineering Group, NTNU
UNIS, Arctic Technology
The water molecule
When oxygen makes 2 covalent bonds as in water, H2O, it
is surrounded by four electron pairs. ROO = Å, ROH =
Å
2 bonding pairs and 2 lone pairs, in roughly tetrahedral
arrangement (°)
Hydrogen bonding
Hydrogen bond – a chemical bonding which arisesarises whenwhen aa
H atom lies between 2 of the highly electronegative atoms
F, O or N
Accounts for the tetrahedral bonding of the molecules in
ice
In the H bond the H nucleus remains covalently bonded to
one of the O atoms
The strength of the hydrogen bond is intermediate between
that of a covalent bond and the residual van der Waals
interaction -> a melting point mid-way between those of a
covalent crystal like diamond and a rare gas like neon
MolecularMolecular structurestructure
ContinuousContinuous molecularmolecular structurestructure
DefectsDefects inin iceice
Defects Type Remarks
Point Vacancy Water molecule missing from ice structure
defects Interstitial Water molecule not at a structure position
+
H3O Water molecule with additional proton
OH- Water molecule with proton missing
D-defect O-O bond with two protons on or near it.
L-defect O-O bond with no proton on it
Electron excitation Place where an electron is excited from its ground state
Impurity molecule Molecule other than H2O on a H2O site
Line Dislocation Boundary line of a region where part of the crystal has
defects been displaced relative to another part
Plane Stacking fault A plane on which the stacking sequence is not what it
defects should be in the structure
DefectsDefects inin iceice
Water -> Ice
Triple point – 3 phases are in equilibrium: T = K, p =
Pa
H2O expands on freezing
Other examples: Silicone, germanium
Max density at T = °C
The crystals reveal the he