1.Ionic bonding

• Ions are formed when electrons are transferred from one atom to another. E.g. sodium atom loses 1 electron to from sodium ion (Na-)
• Lots of ions that are made up of groups of atoms with overall charge. Called compound ions. E.g. Ammonium NH4+ , Carbonate CO3 2- , Hydroxide OH- , Nitrate NO3- , Sulfate SO4 2-
• Electrostatic attraction holds positive and negative ions together. Very strong. When atoms are held together in lattice it’s called ionic bonding. When oppositely charged ions come together and form ionic bonds it’s ionic compound
• Ionic crystals are faint lattices of ions. Lattice is just regular structure. Structure‘s called ‘giant’ because it’s made up of same basic unit repeated over and over again. In sodium chloride, Na+ and Cl- ions are packed together. Sodium chloride is example of compound with ionic crystal structure.
• Electrical conductivity- ionic compounds conduct electricity when they’re molten or dissolved - but not when they’re solid. Ions in liquid are free to move ( and carry charge ). In solid they’re fixed in position by strong ionic bonds
• Melting points- Ionic compounds have high melting points. Giant ionic lattices are held together by strong electrostatic forces. lots of energy to overcome these forces melting points are very high (810° C for sodium chloride )
• Solubility- ionic compounds tend to dissolve in water. Water molecules are polar - part of molecule has small negative charge, and other bits have small positive charges. Water molecules pull ions away from lattice and cause it to dissolve