Every element in the periodic table can be broadly divided into three categories:
Metals are the electropositive element. Electropositive element tend to donate electrons and form positive ions. For example:
Na \(\rightarrow\) Na+ + e–
Non metals are chemical elements which are highly electronegative in nature i.e. they get attracted towards electrons easily.
Cl + e– \(\rightarrow\) Cl–
In this article, we will be dealing with the chemical properties of metals.
Chemical properties of metals:
- Reaction of metal with oxygen: Metals react with oxygen to form metal oxides. Metals donate electrons to oxygen for the formation of metal oxides. For example:
4K + O2 \(\rightarrow\) 2 K2O
Metal oxides are generally basic in nature but it can also be amphoteric in nature. Amphoteric oxides mean that they are acidic as well as basic in nature. Some of the metals like sodium and potassium react vigorously with oxygen. Whenever sodium or potassium is exposed to air it catches fire. Hence, they are kept in kerosene.
- Reaction of metal with water: Some of the metals react with water to form metal hydroxide whereas some of them do not react. Reactivity with water differs from metal to metal.
Metals like sodium and potassium are highly reactive. They react with water to form alkalis such as sodium hydroxide and potassium hydroxide.
2Na + 2H2O \(\rightarrow\) 2NaOH + H2
Calcium also reacts with water to form calcium hydroxide and hydrogen.
Ca + 2 H2O \(\rightarrow\) Ca(OH)2 + H2
Whereas, magnesium and zinc do not react with cold water. They form their respective oxides when reacted with hot water.
Mg + H2O \(\rightarrow\) MgO + H2
Iron is less reactive than sodium, potassium, calcium, zinc and magnesium. It does not react with cold and hot water, but it reacts with steam to form magnetic oxides.
3 Fe + 4H2O \(\rightarrow\) Fe3O4 + 4H2
- Reaction with dilute acids:
Metals like sodium, potassium, lithium and calcium react vigorously with dilute HCl and H2SO4 to form their metal salt and hydrogen.
While magnesium, zinc, iron, tin and lead does not react vigorously with acids.
Mg + HCl \(\rightarrow\) MgCl2 + H2
Fe + H2SO4 \(\rightarrow\) FeSO4 + H2
Metals which fall below hydrogen in the reactivity series does not react with dilute acids. They cannot displace hydrogen to form a bond with a non-metal anion.
- Reaction of metal with other metal salts:
Metals that are more reactive will readily with less reactive metals. More reactive metal displaces the less reactive metal from its oxides, chlorides or sulphides.
Metal A + Salt solution of \(\rightarrow\) Salt solution of + Metal metal B metal A
Zn + CuSO4 \(\rightarrow\) ZnSO4 + Cu
These chemical reactions can be studied more clearly by knowing the order of metals in the electrochemical reactivity series. Metals are arranged according to the electrode potential of metals. The electrochemical series is shown below:
Knowing this electrochemical series we will get to know which metal can displace which metal in a chemical reaction. Here is the NCERT Solutions for Materials- Metals and Non metals. Click and cross check your answers.’