Properties Of Ionic, Metals Lattice Flashcards
Ionic compounds generally have high melting points, and are relatively hard. Why?
The strong electrostatic attraction of the ionic bonds between the cations and anions requires a significant amount of energy to break. There are no weak intermolecular forces within the ionic lattice.
Ionic compounds are generally brittle - they shatter when sufficient force is applied. Why?
The cations and anions are arranged very specifically in the ionic lattice, such that a checkered pattern where cations are adjacent to the anions. When a force is applied, the layers may be displaced, causing anions to align with other anions, with the same being for cations. This leads to electrostatic repulsion that breaks the lattice.
The solubility in water varies between different ionic compounds, why?
When ionic compounds are dissolved in water, ion-dipole attractions form between the partial negative oxygen of the H2O and the cations. This is the same for the partial positive hydrogens of H2O and the anions. (When dissolved in water, they are said to have an aqueous state (aq).)
Ionic compounds are non conductive of electricity in a solid state why?
In a solid state, there are no free charged particles so the ionic compound cannot conduct electricity.
Ionic compounds can conduct electricity in molten or aqueous states. Why?
In a molten or aqueous state, the cations and anions are free to move throughout the substance (contained). The presence of these free charged particles allow conduction of electricity.
Metals are usually hard, have a high tensile strength and high boiling points. Why?
The electrostatic attraction between the deionised electrons and the metal cations is extremely strong.
Metals conduct electricity in the solid state and in the molten liquid state. Why?
The deionised electrons are free to move throughout the metal lattice. The presence of free charged particles allows metals to conduct electricity.
Metals conduct heat well. Why?
When heat is applied to one part of a metal, the delocalised electrons and cations gain kinetic energy. Since the electrons are free to move around, they can transfer the excess kinetic energy throughout the rest of the lattice.
Metals are malleable (can be shaped by beating or rolling) and are ductile (can be drawn into wire). Why?
When forces are applied to the metal, metal ions move past each other. However the “sea” of delocalised electrons is fluid and can follow the displaced cations. This maintains the electrostatic attraction and metallic bonding.
Metals usually have a high density (mass per unit of volume). Why?
The cations in a metal lattice are packed closely together. The density depends on the mass of the metal ion, their atomic radius, and the way in which they are packed in the lattice.
Metals are generally lustrous (shiny). Why?
The presence of free, delocalised electrons reflect light of all wavelengths, causing the metal to appear shiny or lustrous.
