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Physical properties:

  • soft, can be cut down by knife
  • good electrical and heat conductors
  • low density
  • low mp/bp
  • silvery grey

Chemical properties:

  • readily loses 1 valence e
  • reacts spontaneously with water
  • reacts with o2 to form basic oxides
  • reacts with acid to form H2
  • reactions are exothermic

Properties - Grp I

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Increases going down the group:

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  • size of atom/atomic radius increase, valence electron becomes further away from the nucleus, electrostatic forces of attraction weakens, lose electron easier
  • number of electron shells increase, shield the electrostatic forces of attraction between nucleus and valence electron (shielding effect increases), lose electron easier

Reactivity - Grp I

* Ability to lose valence electron:

  • Easier = more reactive

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Characteristics:

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  • Density increase: mass no. increase while the volumes of the metal remains relatively constant
  • mp/bp decrease: the electrostatic forces of attraction between metal cations and sea of delocalized electron becomes weaker as metal cation becomes larger in size (ionic radius increase)

Down the group… - Grp I

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  • strong reducing agents
  • usually kept submerged in oil to prevent direct contact with oxygen

Extra Info

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+O2

+halogens

+water

Li

red flame

bright flame

vigorously

Na

quickly, yellow flame

quickly, bright flame

readily

K

violently, lilac flame

violently, bright flame

explosively

Rb, Cs

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sinks + explodes

  • Li, Na, K skids on surface of water