Structure of simple ionic crystals

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Structure of simple ionic crystals:

 In ionic crystals lattice positions are occupied by positive and nagatives ions in equivalent amounts. In such crystals positive ions are surrounded by negative ions and vice-versa. Since the coulombic forces holding the oppositely charged ions together in an ionic crystal are non directional, the arrangement of ions in the crystal is largely controlled by the sizes and charges of the ions concerned. Normally, each ion is surrounded by the largest number of oppositely charged ions. The number of oppositely charged ions surrounding an ion is the co ordination number of the ion and is related to the relative sizes of the positive and nagative ions. We will discuss below the different types of ionic compounds, depending upon the relative number of positive and nagative ions present in them.

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Siemens Ozoniser how Siemens Ozoniser work

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Rutile structure

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Rutile structure: The radius radio is in the range 0.73 to 0.41. in rutile (TiO²) each Ti⁴+ ion is octahedrally surrounded by six O²- ions whereas each other O²- ion is surrounded by only three Ti⁴+ ions arranged at the tree corners of a plane triangle. The Co-ordination number of Ti⁴+ and O²+ ions are 6 and 3, respectively. It is not exactly a close packed structure. Ti⁴+ ions in rutile may however, be considered as forming a sufficiently distorted body centred cubic lattice.           Example  compounds  having radius ratio below 0.41 are SiO² and BeF² but these are only a few. The Co-ordination number of Si⁴+ and Be²+ is four and that of O²- is two. However, these are appreciably co-valent.
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Paramagnetic substances

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Paramagnetic substances:   The substances which are weakly attracted by magnatic lines of force are called paramagnetic substances and this phenomenon is called paramagnetism. These substances possesses permanent magnetic dipoles due to the presence of unpaired electrons. These substances lose their magnetic behaviour in the absence of an external magnetic field i.e. their magnetic behaviour is temporary. Examples, many transition metals and their ions i.e. TiO², VO², CuO, FeSO⁴ etc.
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