bonding, structure, properties of matter

• What do all ionic compounds have?


  High melting+boiling points
• Why can't ionic compounds conduct electricity in solid state?


  Ions are fixed. No free ions to carry a charge
• Why do ionic compounds have high melting +boiling points?


  strong electrostatic force of attraction between oppositely charged ions. Strong bonds between ions. Lots of energy needed to overcome attraction.
• What state can ionic compounds conduct in?

  Molten+dissolved in aqueous solution(water). Ions free to move
• What happens when non-metal atoms bond together?

  covalent bond. Share pair of electrons
• What happens to the metal when it reacts with a non-metal?


  loses electron, forms positively charged ion
• What happens to the non-metal when it reacts with a metal


  gains electron, becomes negatively charged ion
• What part of there bonded atom is attracted to the shared pair of electrons(covalent)?

  positively charged nuclei by electrostatic forces
• Where do atoms share and transfer electrons?

  Outer shells(highest energy level)
• Why is graphite softer than diamond?

  No covalent bonds in between layers, graphite has layers that can slide over each other because of weak intermolecular forces.
• Why are the melting and boiling points of simple covalent molecules low?

  Weak intermolecular forces between molecules+molcules are small in size, does not require a lot of energy to break forces
• What is the structure of a metal?

  positive ions in giant regular lattice structure held together by strong electrostatic force between oppositely charged positive metal ions and delocalised electrons. Can conduct electricity because delocalised electrons carry charge through structure
• What are positive ions called?


  cations
• What are negative ions called?


  anions
• Why do atoms gain or lose an electron?

  To have full outer shell
• Why can solutions conduct electricity?


  When dissolved in water rigid lattice structure breaks down, ions are free to move and carry charge through whole structure
• Why do atoms share electrons?

  To have full outer shell like noble gas
• What are the properties of graphite?


  Each carbon atoms forms 3 covalent bonds. High melting+boiling points(strong covalent bonds between carbon atoms, require great deal of energy to break), soft +slippery(no covalent bonds between layers, weak intermolecular forces mean layers can slide over each other, can conduct electricity(delocalised electrons one per carbon atom), solid at room temp(strong covalent bonding)
• What are the properties of a metal?

  solid at room temperature, good conductor of heat and electricity, malleable(layers can slide over each other)
• What do the layers of carbon form?


  hexagonal rings
• What is the structure of diamond?

  Each carbon atom forms 4 covalent bonds. Diamond is very hard because of lots of covalent bonds. High melting+boiling point(strong covalent bonds require lots of energy to break) Cannot conduct electricity no free electrons to carry charge
• What is the structure of Silicon dioxide?(giant covalent structure)

  Forms 4 covalent bonds per carbon atom High melting +boiling point(lots of strong covalent bonds that require lots of energy to break). Doesn't conduct electricity because no free electrons to carry charge through structure
• Why is graphite used as a lubricant?

  Weak intermolecular forces between layers of graphite are weak making graphite soft and slippery
• What is a lubricant?

  substance that reduces friction
• Why are alloys harder than pure metals?

  Alloys are different shapes and sizes, distort layers so its harder for layers to slide(more force needed)
• What is an alloy?

  A mixture of two or more elements where one of the elements is a metal
• What is an example of an alloy?

  steel-has carbon and iron
• Why do metals have high melting and boiling points?

  strong metallic bonding takes of energy to overcome
• What are the advantages and disadvantages of dot and cross diagrams?

  Advantages: shows transfer of electrons, shows which atom the bonding electron comes form Disadvantages: doesn't show the 3D arrangement of atoms and electron shells. Doesn't show relative sizes of particles
• What are the advantages and disadvantages of the ball and stick model?

  Advantages: Shows 3D arrangement of atoms in space. Shows regular repeating pattern of ionic compound. Disadvantages: Doesn't show relative size of atoms. There aren't gaps between the ions
• What are the advantages and disadvantages of 2D representation of molecules?

  Advantages: shows what atoms are in a molecules and how they are connected. Easier to draw. Disadvantages: Doesn't show relative size of atoms. Doesn't give 3D representation of what compound will look like in space.
• What are the disadvantages and advantages of 3D representations of ionic solids?


  Advantages: Show ions arrangement in space. Show regular repeating pattern of giant ionic lattice. Disadvantages: Difficult to draw. Doesn't give information about electrostatic force of attraction between ions.
• What are polymers?

  long chains of repeating units
• How are polymers made?

  By joining together thousands of small identical molecules called monomers
• What are monomers?

  Monomers are often alkene molecules e.g. ethene C2H4
• What 3 things do you need to remember when drawing the repeating unit?

  1.repeating units shows 1 carbon to carbon bond. 2. covalent bonds on either side have to extend outside of brackets(shows that polymer molecules extends out in both directions. 3. The n on the outside of the brackets tells us that polymer contains large size of repeating units joined together.
• Why are most polymers solid at room temperature?

  Intermolecular forces of attraction between the polymer molecules are relatively strong. Lots of energy required to break forces meaning they have a high melting point.
• What is the structure and properties of graphene?

  single layer of graphite so one atom thick. Good conductor of electricity because of delocalised electrons, delocalised electrons carry charge through the structure. Graphene has high melting and boiling point and very strong because of strong covalent bonds which need a lot of energy to break bonds