Properties of Metals (Cambridge O Level Chemistry)

Metals and non-metals

• The Periodic Table contains over 100 different elements
• They can be divided into two broad types: metals and non-metals
• Most of the elements are metals and a small number of elements display properties of both types
  • These elements are called metalloids or semimetals 

The metallic character diminishes moving left to right across the Periodic Table

Properties of metals

• Conduct heat and electricity
• Are malleable (can be hammered and made into different shapes) and ductile (can be drawn into wires)
• Tend to be lustrous (shiny)
• Have high density and usually have high melting points
• Form positive ions through electron loss
• Form basic oxides 

Properties of non-metal elements

• Do not conduct heat and electricity
• Are brittle when solid and easily break up
• Tend to be dull and nonreflective
• Have low density and low melting points (many are gases at room temperature)
• Form negative ions through electron gain (except for hydrogen)
• Form acidic oxides

General chemical properties of metals

• The chemistry of metals is studied by analysing their reactions with water, dilute acid and oxygen
• Based on these reactions, a reactivity series of metals can be produced

Reactivity with water

• Some metals react with water, either warm or cold, or with steam
• Metals that react with cold water form a metal hydroxide and hydrogen gas

metal + water →  metal hydroxide + hydrogen

•  For example calcium:

Ca (s) + 2H₂O (l) → Ca(OH)₂ (aq) + H₂ (g)

• Metals that react with steam form metal oxide and hydrogen gas, for example zinc:

Zn (s) + H₂O (g)  →  ZnO (s) + H₂ (g)

Reactivity with acids

• Most metals react with dilute acids such as HCl
• When acids and metals react, the hydrogen atom in the acid is replaced by the metal atom to produce a salt and hydrogen gas, for example iron:

metal + acid → salt + hydrogen

Fe (s) + 2HCl (aq) → FeCl₂ (aq) + H₂ (g)

Reactivity with oxygen

• Unreactive metals such as gold and platinum do not react with oxygen
• Some reactive metals such as the alkali metals react easily with oxygen
• Copper and iron can also react with oxygen although much more slowly
• When metals react with oxygen a metal oxide is formed, for example copper:

metal + oxygen → metal oxide 

2Cu (s) + O₂ (g) → 2CuO (s)