Acid–base imbalance

2014-02-04T02:29:32Z

98.223.254.231: /* Causes */

{{Orphan|date=February 2009}}
[[Image:Criticalradiusratio.png|thumb|300px|right|''Critical Radius Ratio'']]

In [[condensed matter physics]] the '''cation-anion radius ratio''' is the ratio of the [[ionic radius]] of the cation to the [[ionic radius]] of the anion in a cation-anion [[Chemical compound|compound]]. This is simply given by <math>r_{C} / r_{A}</math>

The allowed size of the cation is determined by the critical radius ratio. If the cation is too small, then it will attract the anions into each other and they will collide hence the compound would collapse, this occurs when the radius ratio drops below 0.155.

At the stability limit the cation is touching all the anions and the anions are just touching at their edges (radius ratio = 0.155). Beyond this stability limit (radius ratio > 0.155) the compound will be [[Chemical stability|stable]].

The below table gives the relation between radius ratio and [[coordination number]]
{| class="wikitable" style="text-align:center;"
!Radius Ratio!!Coordination number!!Type of void!!Example
|-
|<0.155||2||Linear||
|-
|0.155-0.225||3||Triangular Planar||B2CO3
|-
|0.225-0.414||4||[[Tetrahedron|Tetrahedral]]||ZnS,CuCl
|-
|0.414-0.732||6||[[Octahedron|Octahedral]]||NaCl,MgO
|-
|0.732-1.000||8||Cubic||CsCl,NH4Br
|}

[[Category:Condensed matter physics]]
[[Face-centered_cubic]]

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Acid–base imbalance