ch 14 periodic table

• Groups

  • elements in the same group have similar chemical properties and same number of valence electrons
  • down a group, there is a higher tendency to lose electrons as it becomes further from nucleus, less attrative forces ( metallic property )
• Groups and their valence electrons

  • 1-1
  • 2-2
  • 13-3
  • 14-4
  • 15-5
  • 16-6
  • 17-7
  • 18-8
• Periods (left to right)

  • more tendency to gain electrons ( non metallic properties )
  • number of valence electrons increase across a period
  • grp1-13;metallic , grp14;metalloid , grp15-18;non-metallic
• Metals in periodic table

  1. Alkali metals (grp1)
  2. Transition metals (central block w/o group numbers)
• Physical Properties of Alkali metals (grp1)

  • soft, malleable, ductile; cut easily with a knifeb
  • low melting and boiling points
  • low densities
  • good conductor of heat and electricity
  • have 1 valence electron so they lose electrons to form positive ions
• Chemical properties of Alkali metals

  • reacts highly exothermic and violent so stored under oil
  • reacts vigorously with water to form alkaline solutions
  • reacts with acid to produce salt and water
• alkali metal(s) + water(l) -> alkali(aq) + hydrogen(g)
• alkali metal(s) + acid -> salt + water(l)
• trends down group 1

  • MP and BP decrease
  • Density decrease
  • Reactivity increase ; valence electron greater tendency to be lost as atomic radii increases
• Physical Properties of Transition metals ( central block of periodic table )

  • High MP and BP
  • High Density
  • Good conductors
  • Ductile and malleable
• Chemical Properties of Transition metals ( central block of periodic table )

  • form coloured compounds
  • have various oxidation states
  • can form ions of different charges
  • good catalysts due to higher MP and BP and variable oxidation states
• iron is used as a catalyst in the Haber process which is the manufcature of ammonia
• nickel is used as a catalyst in the manufacture of margarine
• Halogens (grp17) have 7 valence electrons each
• Physical properties of halogens

  • exist as diatomic molecules
  • poor conductors
  • brittle
  • coloured
  • low MP and BP
• Chemical properties of halogens

  • reacts vigorously with metals to form halides (salts)
• trends down group in halogens

  • physical state changes from gas to solid
  • colour goes from lighter to darker
  • MP and BP increase
  • reactivity decrease; atoms increase in size, lesser AF & more reactive halogen displaces less reactive halide ion
• Halogens

  • F; pale yellow gas
  • Cl; yellow-green gas
  • Br; red-brown liquid
  • I; purple-black solid
  • At; Black solid
• Group 18 elements are noble gases with full valence shells
• physical properties of noble gases

  • exist as monoatomic elements
  • colourless
  • low MP and BP
• chemical properties of noble gases

  • unreactive as there arent any valence electrons