C3 - structure and bonding

• solid state of matter

  • extremely hard to compress
  • Particles packed in a regular pattern
  • Fixed shape
  • Cannot flow but vibrate
• liquid state of matter

  • extremely hard to compress
  • particles extremely close together
  • take the shape of of container
  • can flow
• gases state of matter

  • extremely easy to compress
  • particles widely spaced
  • spread out and fill space in container
  • move quickly and randomly
• how to change state of substance

  putting in or taking out energy
• what is melting

  • heating a solid to a liquid
  • takes place at melting point
  • Liquid has more kinetic energy than solid
  • Put energy in to convert solid to liquid
  • Needed to break forces of attraction in a solid
• link between forces of attraction and energy

  the more forces of attraction in a particle the more energy needed to break the forces and the higher the melting point
• What is freezing

  • cooling a liquid to a solid
  • Cool a liquid back to melting point
  • Forces of attraction reform
• what is boiling

  • heating liquid to gas
  • takes place at boiling point
• what is condensing

  • cooling a gas to liquid
  • takes place at boiling point
  • forces of attraction reform
• limitations of simple particle models

  • assumes particles are solid spheres - particles have lots of different shapes and are not solid
  • Assumed there are no forces between the particles - majorly impact melting and boiling point
• what outer energy level do group 0 have

  full stable outer shell - unreactive
• key facts of ionic bonding

  • elements react to achieve a full outer energy level
  • achieve stable electronic structure of noble gas
• when does ionic bonding take place

  when a metal and non metal react
• ionic bonding between group 1 and group 7

  • neither have a full energy shell
  • group 1 element looses outer electron
  • electron is gained by group 7 atom
  • group 1 charge is 1+ - an ion
  • group 7 charge is 1- - an ion
  • both have stable electronic structure of Nobel gas
• ionic bonding between group 2 and group 6

  • neither have a full outer energy shell
  • Group 2 element looses 2 outer electrons
  • Those electrons are gained by group 6
  • Group 2 charge - 2+
  • Group 6 charge - 2-
  • Both form ions
• what do ionic compounds form

  • Giant Structures
  • giant ionic lattice
  • every positive ion is surrounded by negative ions
  • 3D structures
  • very strong forces of attraction between ions - electrostatic forces/ionic bonds
• properties of ionic compounds

  • very high melting and boiling points - strong electrostatic forces of attraction need a lot of heat energy to break
  • cannot conduct electricity as solid - ions locked in place by strong electrostatic forces - can vibrate but not move
  • Can conduct electricity when melted - electrostatic forces are broken and can carry charge - ions move not electrons
• What forms a covenant bond

  Non metals
• how does hydrogen get a full outer shell

  • by bonding with another hydrogen molecule
  • by sharing a pair of electrons they form a single covalent bond
• what state are small covenant molecules

  usually gas or liquid at room temperature
• why do small covelant molecules have low melting and boiling points

  • atoms in each molecule are held together by strong covalent bonds
  • there are very weak intermolecular forces
  • as temp increases vibration of molecules increases and breaks weak intermolecular forces and the molecules boil
  • does not require a lot of energy to turn molecules from liquid to gas
• do covalent bonds break when melted or boiled

  No
• how does size link to intermolecular forces

  as size of the covelant molecule increases so does the intermolecular forces
• do small covelant molecules conduct electricity

  no - do not have an overall electronic charge
• what forces do small covelant molecules have

  weak intermolecular forces
• how many covelant bonds do giant covalent structures have

  Millions
• 3 examples of giant covelant structure

  Diamond, silicon dioxide (silica) and graphite
• what state are giant covalent structures

  solid at room temperature - high melting and boiling points
• Why do giant covelant structures have high melting and boiling points

  Strong intermolecular forces and covalent bonds which require a lot of energy to break
• what is diamond formed from

  carbon - needs four covalent bonds to form a full carbon atom
• why is diamond hard

  huge number of carbon atoms joined by covalent bonds
• how to melt a diamond

  • have to break all covalent bonds
  • lots of energy
  • very high melting and boiling points
  • melting point 3700
• can diamond conduct electricity

  no - all of the outer electrons are in covalent bonds - no free electrons to carry electrical charge
• what is silicon dioxide formed from

  silicon and oxygen covalently bonded together
• What is graphite formed from

  Carbon covalent bonds
• key properties of graphite

  • soft and slippery
  • high melting and boiling point
  • good conducter of electricity and heat
• structure of graphite

  • each carbon atom forms covalent bonds to 3 other carbon molecules
  • form hexagonal rings - rings of 6 carbon atoms
  • hexagonal rings are arranged into layers - no covelant bonds between layers - can slide over each other
  • large number of strong covalent bonds
• Delocalised electron in carbon

  • each carbon atom has one electron in outer energy level not in a covalent bond
  • These electrons are released and delocalised
  • These electrons can move and conduct electricity and thermal energy
• structure of graphene

  • single layer of graphite
  • one atom thick
• properties of graphene

  • good conductor of electricity - delocalised electrons that can move through the graphene molecule
  • extremely strong
  • high melting and boiling point - large number of strong covalent bonds