Electron microscopy
Ionic Materials
- Practical Electron Microscopy and Database -
- An Online Book -
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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.


As listed in Table 3222, substances with large bonding energies usually have high melting temperatures.

Table 3222. Bonding energies and melting temperatures of ionic substances.

Bonding type

Bonding energy
Melting point (°C)
kJ/mol kcal/mol eV/Atom, Ion, or Molecule
Typical value 50-1000      
NaCl 640 153 3.3 801
MgO 1000 239 5.2 2800

Note that page3239 describes the correlation between the bonding energies and melting temperatures of different substances.

The energy of valence electrons is directly modified by the bond formation process. Although the core electrons do not directly contribute to the chemical bond formation, their energies are still affected by the corresponding change in the valence charge distribution and then can indirectly reveal the bond properties. For instance, during the formation of an ionic bond, valence electrons are transferred from the cations to the anions. The cation contains less negative valence-electron charge than the neutral atom so that the core electrons interact with a local charge distribution that is more positive than for an isolated atom, and then their energy decreases. On the other hand, the energies of the core electrons in anions increase with respect to the neutral isolated atoms. For this reason, the information from core electrons is more easily extractable. For instance, such energy changes can be easily measured with EELS or photoemission spectroscopy.



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