Chemistry C2

  • Created by: abbiedye
  • Created on: 24-07-18 19:34

How are ions formed?

  • Ions are charged particles (Cl- or Mg2+)
  • Ions are formed when atoms gain or lose electrons
  • They do this to get a full outer shell - outer shells are very stable
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What elements form what ions?

  • Group 1 and 2 elements lose electrons to form positive ions
  • Group 6 and 7 elements gain electrons to form negative ions
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Which groups are most likely to form ions?

  • Groups 1+2 and 6+7
  • Group 1 and 2 elements are metals and lose electrons - positive ions (cations)
  • Group 6 and 7 elements are non-metals and gain electrons - negative ions (anions)
  • Group 1 elements = 1+ ions
  • Group 2 elements = 2+ ions
  • Group 6 elements = 2- ions
  • Group 7 elements = 1- ions
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What is ionic bonding?

  • Ionic bonding = transfer of electrons
  • Metals and non-metals can react together
  • When this happens, the metal atoms lose electrons to form positively charged ions
  • The non-metal atoms gain these electrons to form negatively charger ions
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What are some examples for ionic compounds?

  • Sodium Chloride (NaCl)
  • Magnesium Chloride (MgCl2)
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What are ionic compounds?

  • In ionic compounds, the ions are arranged in a pattern. This is called a giant ionic lattice
  • There are strong electrostatic forces of attraction between oppositely charged ions
  • They have similar properties
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What is covalent bonding?

  • When non-metal atoms bond together, they share pairs of electrons to make covalent bonds
  • Atoms only share electrons in their outer shells
  • Atoms get one extra shared electron for every single covalent bond that they form
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What are simple molecular structures?

  • Simple molecular substances are made up of molecules that contain a few atoms joined together by covalent bonds
  • Substances containing covalent bonds usually have simple molecular structures
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What are giant covalent structures?

  • In giant covalent structures, all the atoms are bonded to each other by strong covalent bonds
  • They have very high melting and boiling points. This is because lots of energy is needed to break the covalent bonds
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What are the properties of simple molecular substa

  • Very strong covalent bonds
  • A weak attraction between molecules
  • Low melting and boiling points
  • Don't conduct electricity (no free electrons)
  • Most substances are gases or liquids at room temperature
  • As molecules get bigger, the strength of intermolecular forces increase
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What are polymers?

  • In a polymer, lots of small units are joined together to form a long molecule
  • All the atoms in a polymer are joined by strong covalent bonds
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What are the structures of carbon?

  • Diamond - each carbon atom forms 4 bonds and takes a lot of energy to break
  • Graphite - layers of carbon atoms, each atom forms three bonds in layers
  • Graphene - a sheet of carbon atoms, hexagons, and the bonds make it strong and light
  • Fullerenes - molecules of carbon - closed tubes or hollow balls
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What are the different allotropes of carbon?

  • Diamond - very hard, high melting point, doesn't conduct electricity - no free electrons
  • Graphite - sheets of hexagons, no bonds between the layers - soft, high melting point - delocalised electron = conduct
  • Graphene - one layer of graphite, light, delocalised electron - conducts
  • Fullerenes - closed tubes - hollow balls, hexagons, pentagons or heptagons, huge surface area
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What is metallic bonding?

  • Metallic bonding involves delocalised electrons
  • Metals are giant structures of atoms. They contain lots of metal atoms bonded together
  • The electrons in the outer shell of the metal atoms are free to move around
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What are alloys

  • Pure metals are too soft and are therefore mixed with other metals to make them harder (alloys)
  • Most metals are alloys as they are combined with two or more other metals to make them stronger
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What are the states of matter?

  • Solids = strong forces, held together in fixed positions, in patterns
  • Liquids = weak forces, free to move, don't keep a fixed shape
  • Gases = very weak forces, free to move, no fixed shape or volume
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What are the different changes of state?

  • Solid -> Liquid = melting
  • Liquid -> Gas = boiling
  • Gas -> Liquid = condensing
  • Liquid -> Solid = freezing
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