C2 Bonding and the periodic table

• What is an allotrope?

  • different forms of the same element
  • E.g - graphite, diamond are all allotropes of eachother becuase their solid carbon
• In diamond how many bonds does each carbon have?

  four
• Describe the structure and bonding of carbon?

  • giant covelent lattice
  • 4 bonds
• Can diamond conduct electricity?

  • it cannot
  • becuase it does not have free delocalised ions or electrons that move freely about the structure to pick up charge
• What are the properties of diamond?

  • high melting points/ boiling points
  • hard
  • doesnt conduct electricity
• In graphite how many covalent bonds does each carbon have?

  three
• Describe the structure and bonding of graphite?

  • each carbon is covalently bonded to three other carbon atoms forming a hexaganol sheet
  • these sheets have interolecular forces between the sheet
  • and delocalised electrons flowing through the structure
• Can graphite conduct electricity?

  • graphite can conduct electricity
  • it has delocalised electrons that can pick up charge
• What are the properties of graphite?

  • high melting point
  • soft and brittle
  • Good conductor of heat & electricity
• Why can graphite be used as a lubricant?

  • carbon atoms arranged in layer
  • forces between layers are week intermolecular forces
  • this means that less energy is required to break these bonds so layers slide over eachother easily
• Does diamond or graphite have a higher melting point?

  • diamond has a higher melting point as it is a giant covalent lattice
  • with strong electrostatic forces of attraction between the shared pairs of electrons and positive nuclei
  • in contrast graphite is a simple molecular structure
  • incudes weak intermolecular forces that require little energy to overcome
• Where are the electrons located in an atom?

  • electrons are found in shells
• What do we mean by electron structure or electron configuration in an atom.

  • the arrangment of electrons within an atom
• How many electrons found in the first, second and third shells of electrons

  • First shell - 2
  • Second and third - 8
• If an atom had 15 electrons in total how many would if have in each shell?

  • first shell - 2
  • second shell 8
  • third shell - 5
• What is meant by an atoms outer shell

  • the shell most furthest away from the nuclei
• Are most elements metals or non metals?

  • metals
• Do metals form positive or negative ions when they react?

  • positive
• Physical properties of metals?

  • strong
  • malleable
  • ductile
  • good conductors of electricity and heat
  • high melting/ boiling points
  • shiny
  • dense
• where are the periodic table are transition metals found?

  • in the middle section between group 3 and group 4
• Give 3 properties of transition metals?

  • good catalyst
  • can make different ions - E.g Cu+, Cu2+
  • ions are often coloured so form colourful compounds
• Do non- metals form a postive or negative charge when they react?

  • negative
• Physical properties of non metals?

  • brittle
  • dull
  • low melting/ boiling points
  • poor conductors of electricity
  • low density
• What is an ion

  • a charged atom or molecule
• How does an atom become an ion?

  • by losing or gain one or more electrons
• When group 1 elements become ions what charge will they have?

  +1
• Do group 0 elements become ions?

  • no
  • they already have a full outer shell of electrons and dont need to gain or lose any
• What are the three types of chemical bonds

  • metalic
  • ionic
  • covalent
• What is an ionic bond

  • an electrostatic force of attraction between the negative ions and positive ions
• why do atoms form ions?

  • to get a full outer shell
  • which makes them more stable
• Describe how an ionic bond forms between a metal and a non metal?

  • the metal atom will transfer one or more electrons so both will get a full outer shell
  • the metal will become postively charged
  • the non metal will become negatively charged
  • the two oppositely charged ions will become attracted by strong electrostatic forces
  • this is called an ionic bond
• What is an ionic compound?

  • a compound containing positive and negative ions held together by electrostatic forces of attraction
• Describe the structure of an ionic compound?

  • giant ionic lattice
  • ions packed tightly together
  • strong electrostatic forces of attraction
• Properties of ionic compound?

  • high melting and boiling points
  • good conductor of heat and electricity - (not when solid)
  • Brittle
• Why do ionic compounds have high melting and boiling point?

  • the strong electrostatic forces of attraction between the ions require lots of energy to overcome
  • therefore the compound has high melting and boiling points
• When do ionic compounds conduct electricity?

  • Aqeuous or molten
  • not when solid becuase the substance needs electrons that a free to move around
• Describe a covalent bond?

  • an electrostatic attraction between 2 shared pairs of electrons and a positive nuclei
• how many electrons are shared in each bond

  • two
• What is a double bond?

  • when their are 2 covalent bonds between the atom
  • so 4 electrons are being shared in total
• What are 3 types of substances covalent bonds can make?

  • polymers
  • giant covalent structures
  • simple molecular structures