Module 6 : PHYSICS OF SEMICONDUCTOR DEVICES
Lecture 32 : Ionic Bond
Ionic Bond
In ionic solids, one of the specis of atoms donates electrons to another specis so that each of the atoms may become more stable by having a noble gas (octet) configuration of electrons. For instance in sodium chloride crystal,
 
$\displaystyle {\rm Na}\ + {\rm Cl} \ \rightarrow {\rm Na}^+{\rm Cl}^-$
 
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  Sodium with an atomic number 11 has an electronic configuration $ 1s^22s^22p^63s^1$ while chlorine with the atomic number 17 has the configuration $ 1s^22s^22p^63s^23p^5$. When the atoms come together, Na gives away one electron and becomes positively ionized while Cl receives one electron and acquires a net negative charge. The negative an the positive ions are held together by electrostatic interaction. Ionic solids are hard, brittle, have high melting points and are poor electrical conductors.
   
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