Here's why:
* Ionic Bonds: These bonds form when one atom donates an electron to another, resulting in a positively charged ion (cation) and a negatively charged ion (anion). The electrostatic attraction between these oppositely charged ions holds them together.
* Regular Repeating Pattern: In ionic compounds, the ions arrange themselves in a highly ordered, three-dimensional structure called a crystal lattice. This structure maximizes the attractive forces between oppositely charged ions while minimizing the repulsive forces between ions with the same charge.
Examples:
* Sodium chloride (NaCl): The sodium ions (Na+) and chloride ions (Cl-) arrange themselves in a cubic crystal lattice.
* Calcium fluoride (CaF2): The calcium ions (Ca2+) and fluoride ions (F-) form a different type of crystal lattice structure.
Key Properties of Ionic Crystals:
* High melting and boiling points: The strong electrostatic forces in the crystal lattice require significant energy to break.
* Brittle: Ionic crystals are brittle because a slight shift in the lattice structure can disrupt the alignment of ions, leading to strong repulsive forces and a fracture.
* Good conductors of electricity when molten or dissolved: The ions in the molten or dissolved state are free to move, carrying electric current.
