bonding

• particle theory

  a theory used to explain the different properties and observations of solids, liquids and gases.
• solid properties

  strong forces

  fixed
• liquid properties

  Definite volume, no definite shape
• gas properties

  will expand to fill any container; can be compressed; molecules relatively far apart; molecules move freely
• how are ions formed?

  When atoms lose or gain electrons
• How are covalent bonds formed?

  when non metals share electrons
• ionic structures

  ionic bonds

  lattice
• properties of ionic compounds

  high melting and boiling points

  strong bonds

  conduct electricity when molten
• Simple molecular substances

  Made up of molecules containing a few atoms joined together by covalent bonds
• Properties of simple molecular substances

  strong covalent bonds between the atoms of each molecule

  weak intermolecular forces between molecules

  low melting and boiling points (so normally gaseous at room temperature)

  cannot conduct electricity
• Giant covalent structure

  every atom is connected by strong covalent bonds

  no weak intermolecular forces as there is only one structure

  high melting and boiling points

  cannot conduct electricity (except graphite)
• Diamond properties

  high melting and boiling point

  strong

  no electricity
• allotrope

  Two substances made from the same element, that are in the same physical state, but that have different structures
• diamond bonding

  each carbon atom forms 4 single covalent bonds so all 4 of the outer shell electrons are used to form covalent bonds
• Why can graphite conduct electricity?

  each carbon atom has one electron, which can move freely, and so is able to carry charge.
• alloy

  A mixture of two or more metals
• Why are alloys harder than pure metals?

  the different sized atoms of the metals distort the layers in the structure, making it more difficult for them to slide over each other