c2 - chemical bonding

• there are three types of bonding : covalent, ionic and metallic
• covalent bonds : involves 2 atoms (non-metal) sharing 1 or more pairs of electrons
• metallic bonds - involves an attraction between positively charged ions and delocalised electrons
• positive ions (cations) - when an atom or molecule loses electrons
• ions are charged particles that form when an atom or molecule either loses or gains electrons
• ionic lattices are giant structures formed by ionic compounds
• The empirical formula of an ionic compound is the simplest ratio of ions possible.
• ionic lattices are held together by strong electrostatic forces of attraction between positive and negative ions
• limitations of simple sphere models : forces between particles not shown, shows particles as solid and shows particles as spherical
• process that lead to a change in state : melting, freezing, boiling and condensing
• ionic compounds can conduct electricity when in solution, ions in the lattice are free to move so charge can flow
• ionic bonds have high melting and boiling points
• Polymers are large, chain-like molecules that can extend for thousands of atoms
• polymers are held together by strong covalent bonds and weak intermolecular forces
• diamond has 4 covalent bonds per carbon atom
• diamond is very hard and has a rigid structure
• diamond has a very high melting point and strong covalent bonds. It doesn't conduct electricity and has no charged particles
• diamond is a giant covalent structure
• graphite has layers of hexagonal rings, no covalent bonds between layers meaning they are soft and slippery, and can slide over each other
• graphite has a high melting point and strong covalent bonds
• fullerenes are forms of carbon, and include nanotubes and buckyballs
• buckminsterfullerene - hollow sphere
• graphene - 1 layer of graphite
• graphene is used to make composites, they are very strong and very light
• nanoparticles are used in electric circuits, as catalysts, sun cream, nanomedicine.
• nanoparticles have a large surface area to volume ratio
• ionic compounds have high melting points and strong forces
• nanoparticles - very small particles
• nitric acid is used to make ammonium nitrate
• diamond has a high melting point
• diamond is made from carbon atoms and has a giant covalent structure
• metals conduct electricity because they are giant structures made up of atoms with delocalized electrons so electrons can flow through the metal
• an alloy is a metal which has different types of atoms. Alloys have distorted layers
• pure copper isnt used in coins because it is too soft
• the same reaction can produce two different products due to different conditions
• alloys are harder than pure metals because the particles are different sizes so there are no rows/layers to slide over
• alloys are mixtures
• it is important for the percentage atom economy of a reaction to be as high as possible because it is important for sustainable development and waste products may be pollutants
• why gold is usually mixed with something else for jewellery : pure gold is soft and expensive
• simple molecules have no overall electric charge, low boiling points and cannot conduct electricity