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Worksheet: Centering in Ionic Lattices

Q1:

The radius of a cation in a cubic ionic lattice is 4 0 % smaller than the radius of the anion. The charges of the cation and anion are equal in magnitude. How many anions are likely in contact with each cation?

Q2:

The radius of a cation in a cubic ionic lattice is 1 0 % smaller than the radius of the anion. The charges of the cation and anion are equal in magnitude. How many anions are likely in contact with each cation?

Q3:

How many complete flourine atoms are present in a single unit cell of flourite ( C a F ) 2 ?

Q4:

N a C l and C s C l both have cubic structures. Why do the chloride ions in C s C l have a higher coordination number than the chloride ions in N a C l ?

  • AChloride ions are much smaller than cesium ions but similar in size sodium ions, so occupy tetrahedral holes in C s C l and octahedral holes in N a C l .
  • BChloride ions are similar in size to cesium ions but much larger than sodium ions, so occupy octahedral holes in C s C l and tetrahedral holes in N a C l .
  • CChloride ions are much smaller than cesium ions but similar in size to sodium ions, so occupy octahedral holes in C s C l and tetrahedral holes in N a C l .
  • DChloride ions are similar in size to cesium ions but much smaller than sodium ions, so C s C l is body-centred cubic while N a C l is face-centred cubic.
  • EChloride ions are much smaller than cesium ions but similar in size to sodium ions, so C s C l is body-centred cubic while N a C l is face-centred cubic.