Topic 4: Chemical Bonding and Structure Flashcards
Cations
Definition.
Atoms that lose electrons to form a noble gas e- configuration and have a positive net charge.
Anions
Definition.
Atoms that gain electrons to form a noble gas e- configuration and have a negative net charge.
Ionic Bonding
Definition (3)
- Sum of all the electrostatic attractive and repulsive forces between all the ions in a lattice.
- Established by the transfer of electrons from one atom to another
- To form ions with complete valence shells
What elements are involved in the formation of an ionic compound?
Reaction between metals and non-metals.
How is an ionic compound formed?
(2)
- When metals react with non-metals, electrons are transferred from the metal to non-metal forming an ion
- Ionic bonds form as a result of the electrostatic attraction between oppositely charged ions, forming a lattice structure.
How are the charged ions arranged in an ionic compound?
Giant ionic lattice
- Each ion is surrounded by 6 ions with opposite charge
- No individual ionic bonds
- Opposite charged ions are packed as close as possible, while same charged ions are as far as possible.
Explanation of volatility of ionic compounds.
- Low volatility
- Ionic compounds have ionic bonds which are very strong, so a lot of energy is needed to break its bonds. At room temperature, there isn’t enough energy to break the lattice.
Explanation of melting point of ionic compounds.
- High melting point
- This is due to the strong electrostatic forces between the oppositely charged ions
- When an ionic solid is melted, the electrostatic forces throughout the lattice must be broken and, because these are so strong, a lot of energy is required
What is the relationship between the charges of the ions of a compound and its electrostatic force?
The force between ions is proportional to the product of the charges.
Explanation of electrical conductivity of solid ionic compounds.
When ionic compounds are solid, the ions are not free to move as there are held in fixed positions; so, they cannot conduct electricity.
Explanation of electrical conductivity of molten ionic compounds.
When ionic compounds melt, the ions are free to move as they are no longer held in the crystal; so, they can conduct electricity.
What particles move when an ionic substance conducts electricity at molten state?
Ions are moving, not electrons.
Explanation of solubility of ionic compounds.
Ions from a lattice structure can be separated by water molecules. This is because the energy released when ions are hydrated by water molecules pays back the energy required to break apart the ionic lattice.
Are all ionic compounds soluble in polar solvents? Why?
No. Ionic compounds are soluble in polar solvents and insoluble in non-polar solvents. Non-polar solvents like kerosene, benzene are not capable of dissolving ionic solids since they cannot decrease the forces of attraction between the ions.
