Properties of Ionic Solids

Vocabulary flashcards summarizing key terms and properties related to the structure, bonding, and behavior of ionic solids.

Ionic Solids

A 3D lattice of alternating cations & anions held together by strong ionic (electrostatic) bonds.

Ionic Bond (Electrostatic Attraction)

Strong force of attraction between oppositely charged ions that holds an ionic lattice together.

Melting Point + Boiling Point (Ionic Solids)

High - ions are held together by very strong ionic bonds (electrostatic forces), which means lots of energy is required to break the bonds. (W)

Electrical Conductivity – Ionic Solids

Doesn’t conduct electricity when solid because ions are in fixed positions and cannot move

Electrical Conductivity – Molten/Aqueous Ionic Solid

Conducts electricity because ions are free to move and carry charge.

Hardness (Ionic Solids)

Hard due to the strong ionic bonds between the ions

Brittleness (Ionic Solids)

Brittle - The ions are in fixed positions therefore if a force is applied, the ions are moved out of position, like charges lineup and the repulsive forces push the ions apart and the crystal breaks.

Solubility of Ionic Solids in Polar Solvents

yes due to the strong interactions between solvent molecules and the ions, which can disrupt the ionic lattice.

Hydrated Ion

An ion surrounded by and interacting with water molecules in solution.

Electrostatic Forces

Forces of attraction or repulsion between charged particles; in ionic solids, these forces create strong bonding between cations and anions.

Molecular Solids

Discrete molecules held together by weak intermolecular forces.

Melting Point and Boiling Point (Molecular Solids)

Low - molecules are held together by weak intermolecular forces, which means little energy is required to break the bonds

-The molecules themselves are not broken up – just moved  apart from each other when molten (W)

Electrical Conductivity (Molecular Solids)

Doesn’t conduct electricity as molecular solids do not contain mobile charged particles.

Solubility (Molecular Solids)

Depends on the polarity of the molecular solid and polarity of solvent:

for a substance to dissolve, the solute to solvent attractions must be stronger than the forces of attraction within the solvent and within the solute.

Metals

3D lattice of metal cations surrounded by a sea of delocalised valence electrons. The atoms are held together by non-directional, strong metallic bonds.

Characteristics (Metals)

Metals are malleable and ductile as they have non-directional metallic bonds. It doesn’t matter how the particles are positioned as long as they are surrounded by electrons

Electrical Conditivity (Metals)

Both metal solids and liquids have high electrical conductivity due to the presence of delocalised electrons that can move freely, allowing the flow of electric current.

●Charge is carried by the delocalised electrons which can move throughout the metallic lattice.

Melting and Boiling Points (Metals)

Varied - Metallic bonds tend to be strong, which means lots of energy is required to break the strong metallic bonds. Hence, the melting and boiling points are high (with exceptions).

Covalent Networks

3D array of atoms held together by covalent bonds

Graphite

2D layers of carbon atoms covalently bonded to three other carbon atoms.

Three of carbon's valence electrons are involved in the bonding. The fourth is delocalised between the layers.

The layers are held together by weak forces.

Electrical Conductivity (graphite)

conducts electricity due to the delocalised electrons which are free to move and carry charge through the network (The only non-metallic element, and the only covalent substance that does)

Characteristics (Graphite)

Slippery - can be used as a lubricant. The weak forces between the layers mean they can easily slide over each other

Diamond

Diamond - 3D array of carbon atoms covalently bonded in a tetrahedral arrangement.

Silica (SiO2)

Silica - 3D array of oxygen and silicon atoms covalently bonded

Hardness (Diamond and Silica)

Diamond and silica are very hard due to the strong covalent bonds between the atoms.

Melting and Boiling Points (D+S)

Giant covalent network solids have very high melting point due to the strong covalent bonds between the atoms. (intramolecular?)

●Graphite melts at 3600 ^oC

Diamond sublimes at 5000^oC

Electrical Conductivity (D+S)

None as there are no charged particles.

Solubility (Giant Covalent Networks)

Do not dissolve in water due to the strong covalent bonds between the atoms.

Solubility of Ionic Solids in Non Polar Solvents

Iower solubility than in polar solvents because polar solvents can effectively solvate the ions of ionic compounds, whereas non-polar solvents cannot overcome the strong electrostatic forces holding the ionic lattice together. 

Graphite

Carbon atoms are arranged in layers, with each atom covalently bonded to three others within the layer. The layers are held together by weaker intermolecular forces, allowing them to slide past each other.

Silica

A network of silicon and oxygen atoms, where each silicon atom is bonded to four oxygen atoms, and each oxygen atom is bonded to two silicon atoms, forming a three-dimensional structure.