Chemistry – Acids, bases and salts - Oxides | e-Consult

Generally, oxides of metals tend to be basic, while oxides of non-metals tend to be acidic. This relationship stems from the electronegativity difference between the element and oxygen. Metals have low electronegativity and tend to lose electrons to form positive ions. When a metal reacts with oxygen, it forms a positive oxide ion (Mⁿ⁺). The resulting Mⁿ⁺ ion has a strong attraction for the negatively charged oxygen atoms in water, leading to the formation of hydroxide ions (OH^-) and a basic solution.

Non-metals have high electronegativity and tend to gain electrons to form negative ions. When a non-metal reacts with oxygen, it forms a negative oxide ion (X^-). The resulting X^- ion has a weak attraction for the positively charged hydrogen ions (H⁺) in water, leading to the formation of hydronium ions (H₃O⁺) and an acidic solution.

Examples:

• Sodium oxide (Na₂O) is basic. Sodium is a metal with low electronegativity. Na₂O reacts with water to form sodium hydroxide (NaOH), a strong base.
• Carbon dioxide (CO₂) is acidic. Carbon is a non-metal with high electronegativity. CO₂ reacts with water to form carbonic acid (H₂CO₃), which donates protons (H⁺) to water, resulting in an acidic solution.