The P Block

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The P Block

• Nitrogen and Group 5

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Group 5

• Is at the centre of the periodic table
• Top of group, non-metals
• Nitrogen and Phosphorus
• Bottom of group, metalloids (metallic elements
  with non-metal character)
• Antimony and Bismuth

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Group 5

• Group 5 elements can form 3 covalent bonds
• Sharing the 3 unpaired electrons
• Gives compounds with oxidation state of 3 or 3
  for group 5 element
• Each atom has a lone pair of electrons
• Enables atoms to form dative covalent bonds
• When they do this Group 5 elements can form some
  compounds with oxidation state of 5 for the
  Group 5 element

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Nitrogen

• Very abundant element
• Very unreactive!
• N2 unreactive because of strong triple bond
  holding Ns together
• Bond enthalpy of N N is 945 kJ mol-1
• (Bond enthalpy of N-N is 158 kJ mol-1)
• Hence most reaction of N2 have high EA and
  require high T and catalysts to make them occur
• Haber process- high T Fe catalyst.
• Lightning or gt2000ºC to make N2 react with O2

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Ammonia

• Ammonia is nitrogen hydride, NH3
• Lone pair not involved in bonding
• Dative covalent bonds (dcbs) possible

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Ammonia

• NH3 is a base and forms dcbs to H ions to give
  ammonium ions (NH4)
• Remember once dcbs formed no different from
  cbs!
• NH3 also forms dcbs with TM ions and is a good
  ligand in complexes (see earlier!!)

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Nitrogen Oxides
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Nitrogen Oxides
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Nitrates

• 2 Kinds of nitrate ions involved in the nitrogen
  cycle
• Nitrate(III), NO2-
• Nitrate(V), NO3-
• Both are called nitrates, but distinguished by
  showing OS of N

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Bonding in Nitrates
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Nitrates