Q4 of 68 Page 30

What is meant by the term 'coordination number'?

Coordination number is the number of nearest neighbours of any constituent particles present in the crystal lattice.

What makes a glass different from a solid such as quartz? Under what conditions quartz could be converted into glass?

Classify each of the following solids as ionic, metallic, molecular, network (covalent) or amorphous.

(i) Tetra phosphorus decoxide (P₄O₁₀) (vii) Graphite

(ii) Ammonium phosphate (NH₄)₃PO₄ (viii) Brass

(iii) SiC (ix) Rb

(iv) I₂ (x) LiBr

(v) P₄ (xi) Si

(vi) Plastic

What is the coordination number of atoms:

(a) in a cubic close-packed structure?

(b) in a body-centred cubic structure?

How can you determine the atomic mass of an unknown metal if you know its density and the dimension of its unit cell? Explain.