Describe some characteristics of an ionic compound such as \(\mathrm{KF}\) that would distinguish it from a covalent compound such as benzene \(\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)\).

Ionic compounds boast several defining traits that set them apart from other chemical compounds. These are primarily due to the nature of ionic bonds—the attractions between oppositely charged ions. Ionic compounds are often formed when a metal reacts with a non-metal, resulting in positively charged cations and negatively charged anions. These ions align in a fixed, three-dimensional pattern known as a crystalline lattice structure, which confers solidity and distinct shapes to these substances. Ionic compounds tend to be hard and brittle, meaning they can shatter when enough force is applied. Their stable lattice structure also bestows high melting and boiling points upon them, as a substantial amount of energy is required to break the ionic bonds within the lattice. Moreover, they’re known for their electrostatic attractions, which allow them to conduct electricity when in molten form or dissolved in an aqueous solution. This is due to the free movement of ions, which carry the electrical current.

A cornerstone of an ionic compound's identity is its crystalline lattice structure. This structure involves a repeating, orderly arrangement of ions, creating a solid material that, when viewed under a microscope or x-ray crystallography, reveals a pattern resembling a grid or scaffolding. The arrangement ensures maximum stability due to the ionic bonds' strength, holding the ions at precise distances from one another. Not only does the lattice contribute to the compound's physical strength, but it also influences other characteristics such as solubility and the formation of crystal facets. This organized structure is responsible for the distinctive crystalline shapes often seen in common table salt and other ionic compounds.

Ionic compounds have a unique property in their ability to conduct electricity, yet this is only the case under certain conditions. In the solid state, ionic compounds do not conduct electricity because the ions are locked into the lattice structure. However, when melted or dissolved in water, the lattice breaks down, and the ions are free to move. This mobility allows the free ions to carry an electrical charge, making the liquid or solution a conductor. This characteristic is pivotal in applications such as electrolysis, where an ionic solution is decomposed by passing an electrical current through it.

Covalent compounds, in contrast to ionic ones, form when two or more non-metal atoms share one or more pairs of valence electrons, creating covalent bonds. These shared electrons glue the atoms together, resulting in molecules that could be a single entity or feature a network structure. Covalent bonds generally make these compounds more flexible and less brittle compared to ionic compounds. They commonly have lower melting and boiling points because the energies required to break the intermolecular forces present in covalent compounds are significantly less than those needed to break the ionic bonds in a lattice. Covalent molecules can vary greatly in their properties, depending in part on their polarity. Non-polar covalent compounds do not conduct electricity, making them insulators, while polar ones may show slight conductivity, an exception in the covalent family.

When comparing ionic and covalent compounds, their distinctive properties help distinguish one from the other. Ionic compounds are usually crystalline solids with high melting and boiling points, while covalent compounds could be gases, liquids, or solids with generally lower melting and boiling points. The stark contrast in conductivity is another major point of comparison, with ionic compounds conducting electricity when dissolved in water or molten, whereas covalent compounds are typically non-conductors unless they’re polar. The brittle nature of ionic compounds stands in contrast to the more malleable covalent ones, which are more likely to bend than break. Understanding these differences is fundamental in predicting the behavior and potential applications of various substances in industries like pharmaceutics, materials science, and electronics.