General Chemical Properties of Metals:

(a) Reaction with Oxygen:
Metals react with oxygen to form metal oxides. Most metal oxides are basic in nature, but some are amphoteric. More reactive metals react vigorously, while less reactive ones react slowly or on heating.
Example: $4Na(s) + O_2(g) \rightarrow 2Na_2O(s)$ (Sodium oxide, basic)
$2Al(s) + 3O_2(g) \rightarrow 2Al_2O_3(s)$ (Aluminium oxide, amphoteric)

(b) Reaction with Water:
Metals react with water to form metal oxides or hydroxides and hydrogen gas. The reactivity varies:
• Highly reactive metals (K, Na, Ca) react vigorously with cold water: $2Na(s) + 2H_2O(l) \rightarrow 2NaOH(aq) + H_2(g) + Heat$
• Less reactive metals (Mg) react with hot water: $Mg(s) + 2H_2O(hot) \rightarrow Mg(OH)_2(s) + H_2(g)$
• Metals like Al, Zn, Fe react with steam: $2Al(s) + 3H_2O(steam) \rightarrow Al_2O_3(s) + 3H_2(g)$
• Least reactive metals (Cu, Ag, Au, Pt) do not react with water or steam.

(c) Reaction with Dilute Acids:
Metals above hydrogen in the reactivity series react with dilute acids to produce metal salt and hydrogen gas. More reactive metals react more vigorously.
Example: $Zn(s) + 2HCl(aq) \rightarrow ZnCl_2(aq) + H_2(g)$
Metals below hydrogen in the reactivity series (Cu, Ag, Au, Pt) do not react with dilute acids to release hydrogen.

(d) Reaction with Salt Solutions of Other Metals:
A more reactive metal displaces a less reactive metal from its salt solution.
Example: $Fe(s) + CuSO_4(aq) \rightarrow FeSO_4(aq) + Cu(s)$
(Iron displaces copper because iron is more reactive than copper.)
If a less reactive metal is added to a salt solution of a more reactive metal, no displacement reaction occurs.