Question

Question: Predict the structure of each of the following silicate minerals (network, sheets, double chains, and so forth). Give the oxidation state of each atom.

(a)Apophyllite,${\mathrm{KCa}}_4\left({\mathrm{Si}}_8{\mathrm{O}}_{20}\right)\mathrm{F}.8{\mathrm{H}}_2\mathrm{O}$

(b)Rhodonite,${\mathrm{CaMn}}_4\left({\mathrm{Si}}_5{\mathrm{O}}_{15}\right)$

(c)Margarite,${\mathrm{CaAl}}_2\left({\mathrm{Al}}_2{\mathrm{Si}}_2{\mathrm{O}}_{10}\right){\left(\mathrm{OH}\right)}_2$

Short answer

a) Apophyllite has Infinite Sheet Structure and the oxidation state of K is +1, Ca is +2, O is -2, F is -1, H is +1, and Si is +4.

b) Rhodonite has Closed Ring Structure and the oxidation state of Ca is +2, O is -2, Si is +2 and Mn is +2.

c) Margarite has Sheet Structure and The oxidation state of Ca is +2, O is -2, Al is +3, H is +1, and Si is +4.

Step-by-step solution

a) Apophyllite, KCa4Si8O20F.8H2O

In, apophyllite, ${\mathrm{KCa}}_4\left({\mathrm{Si}}_8{\mathrm{O}}_{20}\right)\mathrm{F}.8{\mathrm{H}}_2\mathrm{O}$the ratio of oxygen and silicon is 2.5:1 so apophyllite has an Infinite Sheet Structure.

According to the periodic table, The oxidation state of K is +1, Ca is +2, O is -2, F is -1, H is +1, and Si is +4.

(b) Rhodonite, CaMn4Si5O15

In, Rhodonite, ${\mathrm{CaMn}}_4\left({\mathrm{Si}}_5{\mathrm{O}}_{15}\right)$the ratio of oxygen and silicon is 3:1 so apophyllite has a Closed Ring Structure.

According to the periodic table, The oxidation state of Ca is +2, O is -2, Si is +2 and Mn is +2.

(c) Margarite, CaAl2Al2Si2O10OH2

In, Margarite, ${\mathrm{CaAl}}_2\left({\mathrm{Al}}_2{\mathrm{Si}}_2{\mathrm{O}}_{10}\right){\left(\mathrm{OH}\right)}_2$the ratio of oxygen and silicon is 3:1 so apophyllite has a Sheet Structure.

According to the periodic table, The oxidation state of Ca is +2, O is -2, Al is +3, H is +1, and Si is +4.