Ions and Ionic Bonding

Ions are atoms or groups of atoms with a positive or negative charge. They are formed when atoms lose or gain electrons.
Atoms that lose electrons become positively charged ions or cations, as they have more protons than electrons.
Atoms that gain electrons become negatively charged ions or anions, as they have more electrons than protons.
The charge on an ion is usually equal to the number of electrons lost or gained by the atom.
For example, when sodium loses an electron, it becomes a positive ion (Na+), when chlorine gains an electron, it becomes a negative ion (Cl-).
The number of protons in an ion does not change during this process, only the number of electrons does.

An ionic bond is the force of attraction between oppositely charged ions in a compound.
Ionic bonding typically occurs between metals and non-metals. Metals tend to lose electrons and form positive ions, non-metals tend to gain electrons and form negative ions.
When a metal atom reacts with a non-metal atom, the metal atom donates electrons to the non-metal atom. This results in the formation of positive and negative ions that attract each other and form an ionic bond.
For example, sodium donates an electron to chlorine to form sodium chloride (NaCl). Sodium becomes a positive ion and chlorine becomes a negative ion. The opposite charges attract and bond together to form NaCl.
An ionic compound is a giant structure of ions. It’s not made up of molecules, but rather a repeating pattern of ions. This pattern is called a crystal lattice.
Ionic compounds have high melting and boiling points due to the strong attractions between the positive and negative ions in the crystal lattice.
Most ionic compounds are soluble in water because the water molecules can separate the ions from the crystal lattice.
Ionic compounds conduct electricity when molten or in solution, but not when solid. This is because the ions can move and carry charge when free, but not when fixed in position within the crystal lattice.

High melting and boiling points: This is due to the strong attractions between the positive and negative ions in the crystal lattice.
Good conductors of electricity when in molten state or in aqueous solution: This is because ions are mobile and can carry charge in these states.
Soluble in water: Water molecules are polar and so can attract the charged ions away from the lattice, causing the ionic compound to dissolve.
Hard, brittle crystalline solids at room temperature: The crystal lattice structure contributes to these properties. If the lattice is distorted by an external pressure, ions of similar charges align, repelling each other and causing the crystal to shatter.