Physical properties of metals
Metals are typically shiny, good conductors of heat and electricity, malleable (can be hammered into shape) and ductile (can be drawn into wires). Most have high melting points and high densities.
The reactivity series
Metals can be placed in order of how readily they react – the reactivity series. A more reactive metal loses electrons more easily to form positive ions.
Key idea
Order (most → least reactive): K > Na > Ca > Mg > Al > Zn > Fe > (H) > Cu > Ag > Au.
Metal + acid → salt + hydrogen (only for metals above hydrogen).
Chemical reactions
- With water: K, Na and Ca react with cold water; Mg and below react only with steam or not at all.
- With acids: metals above hydrogen give a salt and hydrogen; copper (below H) does not react.
Worked example
A zinc strip is placed in blue copper(II) sulfate solution. What happens?
Zinc is more reactive than copper, so it displaces it:
Zn + CuSO4 → ZnSO4 + Cu
The blue colour fades and a red-brown coating of copper forms on the zinc.
Remember
- More reactive metal → loses electrons more readily → displaces a less reactive metal.
- Very reactive metals (above carbon) are extracted by electrolysis.