Section 4 - Ionic Compounds Flashcards
Why do ionic compounds produce giant lattices?
As ionic bonds do not work in any particular direction. The electrostatic attraction is just as strong in all directions around the ion.
Describe the structure of a lattice formed by ionic bonding
The lattice is a closely packed regular array of ions, with each negative ion surrounded by positive ions and vice versa. The forces between the oppositely charged ions are very strong.
What does ionic bond strength depend on?
The charge on the ions. The bigger the charges on the ions, the stronger the attraction.
What are the 3 physical properties of ionic compounds?
1) Melting points: In order to melt a solid, the forces holding the particles together have to be overcome. In an ionic solid, these bonds are very strong, so a large amount of energy is required to break them. So, ionic compounds have very high melting points.
2) Electrical conductivity: In their solid form, ionic compounds are electrical insulators (they don’t conduct electricity). They have no free ions or electrons to carry electric charge. When molten or dissolved, the ions separate and are free to move and conduct electricity. So all ionic compounds conduct electricity when molten or dissolved.
3) Solubility: In many cases ionic compounds are soluble in water. This happens because water is a polar molecule (the positive end of the molecule points towards the negative ions and the negative end towards the positive ions). Although lots of energy is required to break the strong bonds within the lattice, it is provided by the formation of many weak bonds between the water molecules and the ions in solution.
