Crystal Chemistry
Bonding and Ionic Radii
, Chemical Bonding in
Minerals
Bonding forces are electrical in nature (related to
charged particles)
Bond strength controls most physical and
chemical properties of minerals
(in general, the stronger the bond, the harder
the crystal, higher the melting point, and the lower
the coefficient of thermal expansion)
Five general types bonding types:
Ionic Covalent Metallic
van der Waals Hydrogen
Commonly different bond types occur in the
same mineral
, Ionic Bonding
Common between elements that will...
1) easily exchange electrons so as to stabilize their outer
shells (i.e. become more inert gas-like)
2) create an electronically neutral bond between cations
and anions
Example: NaCl Na (1s 2s 2p 3s ) –> Na (1s 2s 2p ) + e
2 2 6 1 + 2 2 6 -
Cl (1s22s22p63s23p5) + e- –> Cl- (1s22s22p63s23p6)
, Properties of Ionic Bonds
Results in minerals displaying
moderate degrees of hardness and
specific gravity, moderately high
melting points, high degrees of
symmetry, and are poor conductors
of heat (due to ionic stability)
Strength of ionic bonds are related:
1) the spacing between ions
2) the charge of the ions
Bonding and Ionic Radii
, Chemical Bonding in
Minerals
Bonding forces are electrical in nature (related to
charged particles)
Bond strength controls most physical and
chemical properties of minerals
(in general, the stronger the bond, the harder
the crystal, higher the melting point, and the lower
the coefficient of thermal expansion)
Five general types bonding types:
Ionic Covalent Metallic
van der Waals Hydrogen
Commonly different bond types occur in the
same mineral
, Ionic Bonding
Common between elements that will...
1) easily exchange electrons so as to stabilize their outer
shells (i.e. become more inert gas-like)
2) create an electronically neutral bond between cations
and anions
Example: NaCl Na (1s 2s 2p 3s ) –> Na (1s 2s 2p ) + e
2 2 6 1 + 2 2 6 -
Cl (1s22s22p63s23p5) + e- –> Cl- (1s22s22p63s23p6)
, Properties of Ionic Bonds
Results in minerals displaying
moderate degrees of hardness and
specific gravity, moderately high
melting points, high degrees of
symmetry, and are poor conductors
of heat (due to ionic stability)
Strength of ionic bonds are related:
1) the spacing between ions
2) the charge of the ions
