Metallic Bonds: • Metal atoms form bonds when the outer energy levels overlap. • This is called the Electron Sea Model. • It proposes that all the metal atoms in a metallic solid donate their electrons to form a “sea” of electrons. • These free moving electrons are also called delocalized electrons.
Properties of Metals • Conduct electricity and heat • High melting and boiling points • Hard and dense • Metals are malleable (hammered into sheets) and ductile (drawn into a wire). • Form alloys (a mixture of elements that have metallic properties). • Examples: steel, bronze, cast iron, gold 10 carat, brass.
IONIC CRYSTALS • In ionic compounds, the positive and negative ions are packed into a pattern. • This particle packing forms an ionic crystal. • Crystals require a large amount of energy to break apart.
CRYSTAL LATTICE • Attraction between + and - ions results in a crystal lattice. • Each positive ion is surrounded by negative ions.
LATTICE ENERGY • Lattice energy = the energy released when an ionic crystalline compound is formed. • The more negative the lattice energy, the stronger the force of attraction between ions • Smaller ions have more negative lattice energy • Higher charges make for more negative lattice energies (example: MgO has more lattice energy than NaF)
Ionic Properties • Made of crystals • Have high melting points • Often soluble in water • Conduct electricity in water