Properties of Metals Chapter 4

• antimony (Sb)


  Metal or non-metal?
• iodine (I), iron (Fe), copper (Cu), phosphorus (P), sulfur (S), magnesium (Mg)


  Metal or non-metal?
• The periodic table is a list of all the known elements which are arranged according to the similarities in their properties.
• Metals and non-metals in the periodic table

  • Non-metals are mostly on the right
  • Metals are on the left and in the centre
• Metalloids


  Sometimes behave like metals and sometimes like non-metals
• Metals are on the left and in the centre
• Non-metals are mostly on the right
• Properties of metals


  • Strong
  • Dense
  • Shiny
  • Malleable (easy to bend)
  • High melting point
  • Sonorous (makes a sound)
  • High boiling point
  • Ductile (can be drawn into wires)
  • Good conductor of electricity
  • Good conductor of heat
• Do all metals have these properties?
• General properties of most metals

  • Solid at room temperature
• Why do metals have these particular properties?

  Typical properties of metals: high melting point, good conductors of electricity and heat, malleable, ductile, strong, dense
• Do all metals behave in the same way?
• Alkali metals


  The elements in group 1, on the left of the periodic table
• Properties of alkali metals

  • Very reactive
  • Rarely found in nature in their elemental form
• Electron structure of alkali metals


  One electron in their outer shell
• Alkali metals have similar physical and chemical properties
• Alkali metals can readily lose the outer shell electron


  To form positive ions with a +1 charge and a full outer shell
• Why are they called the 'alkali metals'?

  • They are so reactive that, as elements, they have to be stored in oil to stop them reacting with oxygen in the air
  • They react with water and form alkaline compounds
• Properties of alkali metals

  • Shiny
  • Good conductors of heat and electricity
  • Soft, can be cut by a knife (softness increases going down the group)
  • Low density (lithium, sodium and potassium float on water)
  • Low melting and boiling points
• Alkali metals share some properties with typical metals
• Density of alkali metals


  Generally becomes more dense going down the group, but the trend is not perfect because potassium is less dense than sodium
• Water has a density of 1 g/dm3
• Which elements in group 1 will float on water?
• Melting points and boiling points of alkali metals

  Decrease going down the group
• Why do the melting and boiling points decrease going down group 1?

  The atoms get larger, so the attraction between the positive metal ions and the delocalized sea of electrons gets weaker, making them easier to melt and boil
• Transition metals


  The elements in the centre section of the periodic table
• Properties of transition metals

  • More dense than main group metals
  • Harder than main group metals
  • Higher melting and boiling points than main group metals
  • Some are strongly magnetic
• Structure of metals


  • Atoms in tightly-packed layers forming a regular lattice structure
  • Outer electrons separate from atoms and create a 'sea of electrons'
  • Electrons are delocalized and free to move through the whole structure
  • Metal atoms become positively charged ions attracted to the sea of electrons (metallic bonding)
• How does the sea of electrons affect the properties of metals?

  Allows metals to conduct heat and electricity efficiently
• Why do metals have high melting points?

  Due to the strong attraction between the positively-charged metal ions and the sea of electrons
• How do metals conduct heat and electricity?

  The delocalized electrons in metallic bonding allow efficient heat and electricity conduction
• Why are metals strong?

  The metallic bonds do not break because the delocalized electrons are free to move throughout the structure, allowing the layers of metal ions to slide over each other without shattering
• Why are metals dense?

  The positively charged metal ions (cations) in the lattice are densely packed together
• Reactivity of metals


  • potassium
  • sodium
  • calcium
  • magnesium
  • aluminium
  • zinc
  • iron
  • lead
  • (hydrogen)
  • copper
  • silver
  • gold
• Reactivity series


  List of metals ordered by how reactive they are, the more reactive the metal the more vigorous the reaction
• A metal that is below hydrogen will not react with dilute acids
• Reactivity with water +
• Reactivity with water:

  • Going down a group, the reactivity of the metal in water  Increase
• Transition metals:

  Transition metals are generally less reactive with water than group 1 and group 2 metals are. For example, iron reacts fairly slowly with water. Gold and platinum are essentially unreactive.
• Reactivity with acids : More metals react with acids and the reactions tend to be more energetic.