### Theory:

When a material undergoes a chemical change or reaction, the chemical property is a trait or activity that can be observed. Chemical properties may be detected during or after the reaction since the arrangement of atoms inside a sample must be disrupted to analyse the property.

Let us see some of the chemical properties of Metals:

Reaction with Oxygen:

Iron on reaction with air and moisture

Metals react with oxygen to form metal oxides.
$\begin{array}{l}\mathit{Metal}\phantom{\rule{0.147em}{0ex}}+\phantom{\rule{0.147em}{0ex}}\mathit{Oxygen}\to \mathit{Metal}\phantom{\rule{0.147em}{0ex}}\mathit{oxide}\\ 2\mathit{Mg}+{O}_{2}\to 2\mathit{MgO}\end{array}$

Reaction with Water:

Metals react with water to form metal hydroxide.
$\begin{array}{l}\mathit{Metal}\phantom{\rule{0.147em}{0ex}}+\mathit{Water}\to \mathit{Metal}\phantom{\rule{0.147em}{0ex}}\mathit{hydroxide}\phantom{\rule{0.147em}{0ex}}+\phantom{\rule{0.147em}{0ex}}\mathit{Hydrogen}\\ 2\mathit{Na}\phantom{\rule{0.147em}{0ex}}+{H}_{2}O\to 2\mathit{NaOH}\phantom{\rule{0.147em}{0ex}}+\phantom{\rule{0.147em}{0ex}}{H}_{2}\end{array}$

Reaction with Acid:

Metals react with acids to form salt and hydrogen gas.
$\begin{array}{l}\mathit{Metal}\phantom{\rule{0.147em}{0ex}}+\phantom{\rule{0.147em}{0ex}}\mathit{Acid}\to \mathit{salt}\phantom{\rule{0.147em}{0ex}}+\phantom{\rule{0.147em}{0ex}}\mathit{Hydrogen}\\ \mathit{Mg}\phantom{\rule{0.147em}{0ex}}+2\mathit{HCl}\to \mathit{Mg}{\mathit{Cl}}_{2}+\phantom{\rule{0.147em}{0ex}}{H}_{2}\end{array}$

Reaction with Base:

Metals react with bases to form salt and hydrogen gas.
$\begin{array}{l}\mathit{Metal}\phantom{\rule{0.147em}{0ex}}+\phantom{\rule{0.147em}{0ex}}\mathit{Base}\to \mathit{Salt}+\mathit{Hydrogen}\\ \mathit{Zn}\phantom{\rule{0.147em}{0ex}}+\phantom{\rule{0.147em}{0ex}}2\mathit{NaOH}\to {\mathit{Na}}_{2}\mathit{Zn}{O}_{2}+{H}_{2}\end{array}$

Displacement reaction:

More reactive metal replaces a less reactive metal from its compound.
$\begin{array}{l}\mathit{More}\phantom{\rule{0.147em}{0ex}}\mathit{reactive}\phantom{\rule{0.147em}{0ex}}\mathit{metal}\phantom{\rule{0.147em}{0ex}}+\phantom{\rule{0.147em}{0ex}}\mathit{less}\phantom{\rule{0.147em}{0ex}}\mathit{reactive}\phantom{\rule{0.147em}{0ex}}\mathit{metal}\phantom{\rule{0.147em}{0ex}}\mathit{compound}\to \mathit{More}\phantom{\rule{0.147em}{0ex}}\mathit{reactive}\phantom{\rule{0.147em}{0ex}}\mathit{metal}\phantom{\rule{0.147em}{0ex}}\mathit{compund}\phantom{\rule{0.147em}{0ex}}+\phantom{\rule{0.147em}{0ex}}\mathit{less}\phantom{\rule{0.147em}{0ex}}\mathit{reactive}\phantom{\rule{0.147em}{0ex}}\mathit{metal}\\ \mathit{Mg}\phantom{\rule{0.147em}{0ex}}+\mathit{Cu}{\mathit{SO}}_{4}\to \mathit{Mg}{\mathit{SO}}_{4}+\mathit{Cu}\end{array}$