Melting and boiling point: giant structures Substances with giant structures generally have high melting and boiling points because all the atoms are strongly bonded together to form a continuous 3D lattice. A large amount of energy is needed to break these bonds. strong covalent bonds holds atoms together strong metallic bonds holds ions together strong ionic bonds holds ions together

Ionic bond=metal and non-metal The electrostatic attraction between oppositely charged ions Metal loses electrons to become positive (cation) Non-metal gains to become negative (anion) 2+ - ATOM ATOM Cl Be Cl Be Be 2,2 Cl 2,8,7 Be2+ [2] 2+ Cl- [2,8,8] -

Ionic bonds ALWAYS FORM GIANT IONIC STRUCTURES not molecules High m.p. and b.p.- lots of strong ionic bonds in the giant ionic lattice, lots of energy to break. Conducts electricity when dissolved or molten- free moving ions, can conduct (solid= ions in fixed position cannot move) Soluble in water-water is polar so opposite charges attract ions out of the lattice.

Covalent bond=non-metal and non-metal The electrostatic attraction between a shared pair of electrons and two nuclei Atoms share up to 3 electron pairs to complete outer shell Learn dot and cross for, O2, H2, Cl2, H2O, CH4, NH3 , HCl , N2, C2H4, CH3OH and CO2

Simple covalent molecules e. g Simple covalent molecules e.g. O2, H2, Cl2, H2O, CH4, NH3 , HCl , N2, C2H4, CH3OH and CO2 Gases and liquids at room temperature, low m.p. and b.p.- ONLY weak forces of attraction between molecules. Do not conduct – no free ions or electrons

Giant covalent structures Uses drilling-its very hard Jewelry-shiny Uses pencils-soft and dark (makes a mark on the page) Lubricant-only weak forces between the layers, can easily slip and slide over each other.

Copy: Metal Structure Definition of a metallic bond -the attraction between the array of positive metal ions and the sea of delocalised electrons. Why ? All metal atoms are arranged in a regular pattern - Lattice Metal atoms have tendency to loose electrons to become stable Delocalised electrons from outer shells of metal Conduct heat Conduct electricity

Examples of Alloys Different types of steel Steel = IRON + CARBON = IRON + CARBON + Chromium / Nickel = IRON + CARBON + Manganese

Brass = Copper + Zinc. Bronze = Copper + Tin Solder = Zinc + Lead Amalgam = Mercury + Silver

When you hit the metal, the layers can slide….. Metal force But for alloys, when you hit, the layers cannot slide…..because the atoms are of different size!! So More STRONG than metals force