What are the three basic types of solids and the composite units of each? What types of forces hold each type of solid together?

Ionic solids consist of a lattice of ions bonded together by strong electrostatic forces. These ions are atoms or molecules that have lost or gained electrons, creating positively charged cations and negatively charged anions. The electrostatic attraction between these oppositely charged ions forms a rigid, crystalline structure.

Common examples of ionic solids include table salt (sodium chloride) and calcium fluoride. These materials tend to have high melting and boiling points due to the strong bonds between the ions. They also conduct electricity when molten or dissolved in water, as the ions are free to move and carry current.

Molecular solids are composed of molecules held together by weaker intermolecular forces, rather than the strong ionic or covalent bonds found in other types of solids. These intermolecular forces include London dispersion forces, dipole-dipole interactions, and hydrogen bonds.

Some typical examples of molecular solids are ice (solid water) and dry ice (solid carbon dioxide). Given their weaker bonds, molecular solids generally have lower melting and boiling points compared to ionic or atomic solids. They are also poor conductors of electricity because there are no free charges available for electrical conduction.

Atomic solids are materials where atoms are the fundamental building blocks. Depending on the type of bonding, they are categorized further into metallic solids, network solids, and noble gas solids.

For instance, metallic solids like copper or iron are held together by metallic bonds, which allow for the 'sea of electrons' that grant metals their characteristic properties such as conductivity and malleability. Network solids, like diamond or quartz, rely on extended networks of covalent bonds, leading to very strong and hard materials. Lastly, noble gas solids, like solid argon, are formed by weak London dispersion forces, as noble gases are non-reactive elements with full valence electron shells.

Intermolecular forces are the forces of attraction that exist between molecules. They are crucial for determining the physical properties of molecular solids, such as boiling points, melting points, and solubility.

Types of Intermolecular Forces:

• London dispersion forces: Temporary dipole-induced attractions, important in noble gas solids and nonpolar molecules.
• Dipole-dipole interactions: Attractions between molecules with permanent dipoles, found in many polar substances.
• Hydrogen bonds: Strong dipole-dipole interactions involving a hydrogen atom bonded to a highly electronegative atom (e.g., oxygen or nitrogen).

The relative strength of these forces, from weakest to strongest, usually follows the order of London dispersion, dipole-dipole, then hydrogen bonding.

Covalent bonds are a form of chemical bond where atoms share pairs of electrons to achieve a full valence shell and gain stability. These bonds form between nonmetal atoms with similar electronegativities.

Materials with covalent bonds can be either molecular or network covalent solids. While molecular covalent solids, like ice, are made up of discrete molecules held together by intermolecular forces, network covalent solids, such as diamond, consist of atoms linked in an extensive network of covalent bonds, resulting in very hard and high-melting-point materials.

Metallic bonds are unique to metallic solids and are characterized by a 'sea of electrons' that flow around a lattice of positive metal ions. These delocalized electrons are responsible for many of the properties of metals, including electrical and thermal conductivity, reflectivity, and the ability to be deformed without breaking (malleability and ductility).

Since the electrons are not bound to any particular atom, they can move freely, which explains why metals can conduct electric current and heat so efficiently. The strength of metallic bonding varies among different metals and alloys, impacting material hardness and melting point.

Electrostatic forces are the attractive or repulsive forces between particles that are caused by their electric charges. In the context of solid-state chemistry, these forces are primarily responsible for holding ionic solids together.

Positive and negative ions are created when atoms gain or lose electrons, respectively, and the resulting charge difference leads to the electrostatic force, which is a central concept in understanding the stability and properties of ionic compounds. The magnitude of this force is governed by Coulomb's law, which states that the force between two charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.