Chapter 18, Problem 8RQ

Why are all crystals of the mineral halite, NaCl, cubic?

Solution

To determine: The crystals of mineral halite, NaCl are cubic in nature.

Answer:

Due the orderly arrangement of particles in three-dimensional array, the crystal structure for, mineral halite, NaCl, is cubic.

Explanation:

The minerals are naturally occurring crystalline solid. This crystalline nature is generated because of ionic bonding present in the minerals. An ionic bond is a bond present between ions. The atoms involved in ionic bonds must have a high difference in electronegativity. The atoms with low electronegativity tend to lose electrons and generate a positive ion and the atoms with high electronegativity tend to gain electrons and generate a negative ion.

The positive and the negative ions tend to attract together by the electrostatic force of attraction and that generates an ionic bond between them. The ionic compounds are usually found in a form of crystals.

In sodium chloride, NaCl, each cation (sodium ion) gets surrounded by six anions (chloride ions) and each negatively charged chloride ion gets surrounded by six cations ( (sodium ions). Therefore, overall, there is only one sodium ion for each chloride ion.

So due the orderly arrangement of particles in three-dimensional array, the crystal structure for, NaCl, is cubic.

Conclusion:

Therefore, due the orderly arrangement of particles in three-dimensional array, the crystal structure for, mineral halite, NaCl, is cubic.