2.1 Bonding, Structure & Properties

• Metallic bonding: when metal atoms bond together
• Electrons from outer shells of atoms are delocalised meaning they are free to move through the whole structure
• The strength of a metallic bond is due to the force of attraction between the metal ions (+) and the delocalised electrons (-)
• Conduct electricity: the delocalised electrons carry electrical charge through the structure
• Conduct heat: the delocalised electrons and closely packed ions transfer energy through the structure by conduction
• Malleable or ductile: the layers of metal ions are able to slide over each other when hammered or stretched
• High melting and boiling points: large amounts of energy are needed to break the strong metallic bonds in melting/boiling
• The melting and boiling points increase as you move across any period of the periodic table because there are more delocalised electrons, increasing the attraction between the ions and the free electrons (stronger bonds)
• Ion: a changed particle. It has different numbers or protons and electrons
• Positive ion: has more protons (+) then electrons (-)
• Negative ion: has more electrons (-) than protons (+)
• Ionic bonding: the bonding between metal and non-metal atoms
• Ionic bonds form when electrons transfer from a metal to a non-metal atom so that both atoms achieve full outer shells
• Covalent bonding: the bonding between non-metal atoms
• Covalent bonds form when the atoms share electrons so that both atoms achieve full outer shells
• Ionic lattice: the regular arrangement of the ions in ionic structures
• Oppositely charged ions attract each other in a regular pattern
• Ionic lattice structures have high melting and boiling pony's due to the strength of the electrostatic forces between the ions
• Ionic lattice structures conduct electricity when dissolved or molten - only then are the ions free to move to carry the charge
• Simple molecular structures consists of a few atoms held together by covalent bonds. Hydrogen, water and carbon dioxide are examples of simple molecular structures
• Simple molecular bonds have low melting and boiling points due to the weak intermolecular forces between the molecules
• Simple molecular structures do not conduct electricity as there are no free moving electrons to carry the electrical current
• Giant covelant structures consist of lot of atoms held together by covalent bonds
• Giant covalent bonds are arranged into giant lattices, which are extremely strong because of the large number of bonds in the structure
• Diamond: each carbon bonded to 4 others. It does not conduct electricity and is used in drill bits, glass cutting and gemstones
• Graphite: each carbon bonded to 3 others. It conducts electricity due to the delocalised electrons between layers that carry charges. It is used in pencils and lubricants - layers can slide over each other