Topic D: Models of Bonding and Structure - Ionic Flashcards
Definition of ionic bond
The electrostatic attraction experienced between the electronic charges of a cation and anion
What are the characteristics of an ionic bond
Electrostatic in nature
Usually strong
Non-directional
Definition of lattice energy of an ionic bond
The amount of energy evolved when one mole of the ionic solid is formed from its constituent gaseous ions under standard condition
What is the magnitude of lattice energy dependent on
It is proportional to the charges on the ions
It is inversely proportional to the distance separating the ions
Why does the magnitude of lattice energy decrease after the distance separating the ions becomes too small
When the distance between ions becomes too small, the repulsion between the electron clouds causes the magnitude of lattice energy to decrease
Generally, what causes the strength of ionic attraction to increase
Decreasing the size of the ion
Increasing the charge of the ion
What are typical properties of ionic compounds
High melting and boiling points
Hard but brittle
Good conductors of electricity in molten and aqueous states
Soluble in polar solvents
Insoluble in non-polar solvents
Why do ionic compounds have a high melting and boiling point
A large amount of energy is required to overcome and separate the strong electrostatic attractive forces of attraction between oppositely charged ions
Why are ionic compounds hard
The ions are bound strongly to the lattice and are not easy to displace. Thus the surface of ionic crystals are not easily scratched
Why are ionic compounds electrical conductors in molten and aqueous state
Ther are free mobile ions present to carry the electrical charge
Why are ionic compounds non-electrical conductors in the solid state
The strong electrostatic attractive forces of attraction prevent the movement of charged ions, so they cannot carry the electrical charge
Explain ionic compounds’ solubility in non-polar solvents
Non-polar solvents do not have strong dipoles to pull the ions away from the lattice so the compound does not dissolve
Explain ionic compounds’ solubility in polar solvents
Ionic compounds form ion-dipole attractions that result in the release of energy that causes the detachment of ions from the crystal lattice, allowing the ionic compounds to dissolve.
Why are ionic compounds brittle
Distortion in the ionic compound causes ions of like charges to come close together, where they will then sharply repel
What are the factors affecting the lattice energy of an ionic compound
Charges on the ions
Distance separating the ions (radius of the ions)
