Answer:

Ionic Crystal:
An ionic crystal is a type of crystal structure that is held together by electrostatic forces between positively and negatively charged ions. In an ionic compound, the atoms have gained or lost electrons to form ions with opposite charges. These ions are then attracted to each other to form a crystal lattice.

Lithium Fluoride (LiF):
LiF is an ionic compound composed of lithium cations (Li+) and fluoride anions (F-). Lithium has a +1 charge, while fluoride has a -1 charge. When these ions come together to form LiF, the electrostatic forces between the positive and negative charges hold the crystal lattice structure together.

Explanation:
LiF is an ionic compound because it is composed of positively charged lithium ions (Li+) and negatively charged fluoride ions (F-). The lithium atom loses one electron to become a Li+ ion, while the fluorine atom gains one electron to become an F- ion. The strong electrostatic attraction between these oppositely charged ions leads to the formation of a crystal lattice structure.

In an ionic crystal, the ions are arranged in a repeating pattern throughout the crystal lattice. The positive and negative charges are balanced, resulting in a neutral overall charge for the crystal. The arrangement of ions in an ionic crystal is determined by the size and charge of the ions, as well as the strength of the electrostatic forces between them.

Ionic crystals have high melting and boiling points because the strong electrostatic forces between the ions require a large amount of energy to break. They are also brittle, as the crystal lattice can easily be disrupted by external forces, causing the crystal to shatter.

In the case of LiF, the lithium ions (Li+) and fluoride ions (F-) are arranged in a cubic lattice structure. This arrangement maximizes the attractions between the ions while maintaining a stable structure. The Li+ ions are surrounded by six F- ions, and vice versa.

In conclusion, LiF is an ionic crystal because it is composed of oppositely charged ions held together by strong electrostatic forces. The arrangement of ions in a crystal lattice is determined by the size and charge of the ions, as well as the strength of the electrostatic forces between them.