Year 9 Chemistry EOY Revision

• The ability of an object to transfer heat or electricity to another object.

  Conductivity

  
• Able to be stretched into wires

  Ductile

  
• The attraction between oppositely charged ions

  Ionic bonding

  
• Lattice


  Interconnected atoms or ions, all bonded together to form a pattern.
• Metal


  A class of elements characterized by physical properties that include shininess, malleability, ductility, and conductivity.

  
• Conductivity


  The ability of an object to transfer heat or electricity to another object.

  
• Malleable


  A class of elements characterized by physical properties that include shininess, malleability, ductility, and conductivity

  
• Ductile


  Able to be stretched into wires

  
• Reactivity series


  A list of metals which shows them in order of their reactivity, with the most reactive at the top.

  
• Ionic bonding


  The attraction between oppositely charged ions

  
• Non-metals


  An element that tends to be a poor conductor of heat and electric current; these generally have properties opposite to those of metals.

  
• Valence electrons


  Electrons on the outermost energy level of an atom

  
• Dot and cross model

  +Shows non-bonding electrons

  -Only shows electrons in the outer shell

  Larger molocules can become crowded and confusing
• Limitations of the simple particle model

  -It assumes that all particles are solid spheres (they're not all spheres and none are solid.)

  -It assumes that there are no forces of attraction between particles (it actually has a big role on the m.p./b.p.
• Property of all giant covalent structures

  ★ Very high m.p./b.p.

  ✔︎ Takes a lot of energy to overcome strong covalent bonds
• Structure of metals


  ★ Metal atoms lose their outer shells. This results in:

  ★ Positive ions

  ★ A sea of delocalised electrons
• m.p/b.p of metallic bonds


  ★Very height

  ✔︎ This is because it takes a lot of energy to overcome metallic bonds
• Conduction in metallic bonds


  ★ Metallic compounds are great at conducting heat and electricity

  ✔︎ The delocalised electrons are free to move

  𐬽 They can carry current (and heat)
• Why can pure metals be bent and shape and how can this be a problem?

  ★ Atoms are arranged in layers that can slide past each other

  ★ This means some metals are too soft for use?
• How do alloys make metals harder and more useful?


  ★ An alloy is a mixture of metals

  ★ The different sizes of atoms means that the layers can't slide past each other

  𐬽 Alloys are harder than pure metals
• Structure of diamond


  ★ Each carbon atoms is covalently bonded to 4 others (full outer shell)
• m.p/b.p of diamond


  ★ Diamond has a very high m.p./b.p.

  ✔︎ This is because it takes a lot of energy to take down all the covalent bonds
• Conductivity of diamond


  ★ Diamond cannot conduct electricity

  ✔︎ This is because it has no delocalised electrons to carry charge
• Hardness of Diamond


  ★ Diamond is very hard

  ✔︎ This is due to the strong structure of diamond.
• Structure of graphite


  ★ Each carbon atom is covalently bonded to 3 others

  ★ They form hexagonal grids of six carbon atoms

  ★ These carbon atoms are arranged in layers

  ⚠︎︎ There are no covalent bonds between the layers
• conductivity of graphite


  ★ Graphite can conduct electricit

  ✔︎ This is because each carbon atoms is only connected to 3 others

  ➜ This means that there is 1 delocalised electron free to move

  𐬽 It can carry charge (and thermal energy)

  𐬽 It can conduct heat & electricity
• How is Graphite like metals?

  ★ It can conduct electricity (even though it isn't a metal)
• What is the m.p/b.p of graphite?

  ★ Very high

  ✔︎ This is because it takes a lot of energy to destroy all the covalent bonds
• Why can layers of graphite slide over each other?

  ★ The forces between the layers are very weak

  𐬽 They can easily slip and slide
• What is graphene?


  ★ A single layer of graphite
• What is the strength of graphene and why?

  ★ Very strong

  ✔︎ It has a strong structure with lots of strong covalent bonds