Solid State Online Science Quiz

There are 14 distinct Bravais lattices that describe the possible arrangements of points in a crystal structure in three dimensions.

A unit cell is the smallest repeating unit that, when stacked in three dimensions, generates the entire crystal lattice.

Polymorphism is the ability of a solid material to exist in more than one form or crystal structure.

Graphite consists of layers of carbon atoms arranged in a hexagonal pattern, which defines its hexagonal crystal system.

Schottky defects are point defects in crystal lattices, which are characteristic of solid structures where atoms or ions are missing from their lattice sites.

Quartz (SiO2) is a network covalent solid where silicon and oxygen atoms are linked by covalent bonds in a continuous 3D structure.

The coordination number for hexagonal close packing (HCP) is 12, not 8. A coordination number of 8 is characteristic of a body-centered cubic (BCC) structure.

Vacancy defects are often referred to as thermodynamic defects because they are created when a crystal is heated, causing some lattice sites to become vacant. Frenkel and Schottky defects are stoichiometric defects, but the term 'vacancy defect' specifically describes the loss of atoms due to thermal energy.

Frenkel defects occur in crystals where there is a large difference in size between the cation and anion. KBr has ions of similar size, which favors the formation of Schottky defects instead.

FeO (Ferrous oxide) is a classic example of a metal-deficient defect, where the ratio of iron to oxygen is less than 1:1 due to the presence of Fe(3+) ions replacing some Fe(2+) ions to maintain electrical neutrality.

In XY-type crystals (assuming AB-type like NaCl structure), if X has coordination number 6, then Y also has coordination number 6 due to the symmetrical nature of the structure. In NaCl-type crystals, each Na+ touches 6 Cl- and each Cl- touches 6 Na+.

In the NaCl crystal lattice, each sodium ion is octahedrally surrounded by 6 chloride ions, and each chloride ion is surrounded by 6 sodium ions.

Increasing pressure forces ions closer together, which favors a structure with a higher coordination number to maximize packing efficiency. Thus, NaCl (CN 6) converts to CsCl (CN 8) under high pressure.

Glass is a classic example of an amorphous solid, meaning it lacks a long-range ordered crystalline structure. Diamond, graphite, and common salt are all crystalline solids.