Question

Discuss the acidic and basic nature of metals and non-metals.

Answer 1

Hint: Start this question by keeping in mind the general properties of metals & non-metals and acidity and basicity and try to compare them.

Complete step by step answer:
Let us start this question by defining all terms individually –
Acid is defined as, “a molecule or ion capable of donating a proton (hydrogen ion \[{{H}^{+}}\]) (a Bronsted–Lowry acid), or, alternatively, capable of forming a covalent bond with an electron pair (a Lewis acid)”.
Base is defined as, “any substance, such as the \[O{{H}^{-}}\] ion, that can donate a pair of nonbonding electrons. (a Lewis base)” or “substances that dissociate in aqueous solution to give hydroxide ions (Bronsted-Lowry Theory)”.
Metals are those elements that have a tendency to lose electrons. In the periodic table, metals occur as – alkaline earth metals, alkali metals, transition metals, actinides and lanthanides.
Non-metals are those elements that have a tendency to gain electrons.
Now, from the above discussion, we can draw a conclusion, that oxides of metals are basic in nature whereas oxides of non-metals are acidic.
Metal oxides on being dissolved in water release hydroxyl ions, and are therefore basic.
Non-metallic oxides on being dissolved in water release hydronium ions, and are therefore acidic.
Example –
Sulphur is a non-metal, on reaction with water, it gives an acid –
\[2S+3{{O}_{2}}\to 2S{{O}_{3}}\]
\[S{{O}_{3}}+{{H}_{2}}O\to {{H}_{2}}S{{O}_{4}}\]
Sodium is a metal, on reaction with water, it gives a base –
\[4Na+{{O}_{2}}\to 2N{{a}_{2}}O\]
\[N{{a}_{2}}O+{{H}_{2}}O\to 2NaOH\]

Note: Litmus test is a very easy way to see if a compound is acidic or basic in nature. In an acidic environment, blue litmus turns to red. Whereas, in the basic environment, red litmus turns blue.