# Worksheet: Packing Efficiency

Q1:

In a close-packed system, what percentage of the unit cell is occupied by holes?

Q2:

Which of the following elemental materials contains the fewest atoms per unit volume?

• AArsenic (density 5.73 g/cm3)
• BSilicon (density 2.33 g/cm3)
• CRed phosphorus (density 2.34 g/cm3)
• DGermanium (density 5.32 g/cm3)

Q3:

Calculate to the nearest percent the packing density of the carbon atoms in diamond.

Q4:

In a hexagonal close-packed system, the metal atom caps are arranged in an pattern.

• AAAA
• BABC
• CABB
• DABA

Q5:

A metal has an atomic packing density of . Which type of lattice do the metal atoms form?

• ASimple cubic
• BFace-centered cubic
• CHexagonal close-packed
• DBody-centered cubic
• EDiamond cubic

Q6:

Which of the following lattice structures has the lowest packing density?

• ABody-centered cubic
• BSimple cubic
• CFace-centered cubic
• DDiamond cubic
• EHexagonal close-packed

Q7:

In a face-centred cubic ionic lattice, cations of element occupy half of the octahedral holes between anions of element . The mass of the ion is 66.57% less than the mass of the ion. As a percentage of the total mass, how much of the material is made up of element ?

• A42.9%
• B74.9%
• C60.0%
• D59.9%
• E49.9%