How Do Metals and Non-Metals React?

The reactivity of metals and non-metals is determined by their tendency to lose or gain electrons to achieve a stable electron configuration, similar to noble gases. Metals tend to lose electrons to form positive ions (cations), while non-metals tend to gain electrons to form negative ions (anions). This exchange of electrons forms ionic bonds in compounds. Here’s a detailed explanation of how metals and non-metals react with each other.

Ionic Bond Formation

Metals react with non-metals to form ionic compounds. In these reactions, metals donate electrons to non-metals. As a result:

Metals become cations (positively charged ions).
Non-metals become anions (negatively charged ions).

These oppositely charged ions attract each other to form a stable ionic compound.

Example:

Sodium Chloride ( $\boldsymbol{\textbf{NaCl}}$ ): Sodium ( $\boldsymbol{\textbf{Na}}$ ), a metal, has one electron in its outermost shell. It donates this electron to chlorine ( $\boldsymbol{\textbf{Cl}}$ ), a non-metal that requires one electron to complete its valence shell.
- $\boldsymbol{\textbf{Na} \rightarrow \textbf{Na}^+ + \textbf{e}^-}$
- $\boldsymbol{\textbf{Cl} + \textbf{e}^- \rightarrow \textbf{Cl}^-}$

The electrostatic attraction between $\boldsymbol{\textbf{Na}^+}$ and $\boldsymbol{\textbf{Cl}^-}$ forms sodium chloride ( $\boldsymbol{\textbf{NaCl}}$ ), or table salt.

Real-life Application:

Salt in daily life: Sodium chloride (table salt) is one of the most common ionic compounds used in food and industry. It plays a vital role in human health by regulating fluid balance and nerve function.

Properties of Ionic Compounds

Ionic compounds formed by the reaction between metals and non-metals exhibit distinct properties:

High Melting and Boiling Points: Due to the strong electrostatic forces between the cations and anions, a large amount of energy is required to break the bonds, resulting in high melting and boiling points.
Solubility: Ionic compounds are generally soluble in water but insoluble in organic solvents like kerosene and petrol.
Electrical Conductivity: Ionic compounds conduct electricity when dissolved in water or in the molten state. This is because the ions are free to move and carry electric current.

Example:

Sodium chloride ( $\boldsymbol{\textbf{NaCl}}$ ) dissolves in water to form $\boldsymbol{\textbf{Na}^+}$ and $\boldsymbol{\textbf{Cl}^-}$ ions, which can move freely and conduct electricity.

Formation of Magnesium Oxide (MgO)

Magnesium, a metal, reacts with oxygen, a non-metal, to form magnesium oxide. Magnesium donates two electrons to oxygen, forming a strong ionic bond.

- $\boldsymbol{\textbf{Mg} \rightarrow \textbf{Mg}^{2+} + 2\textbf{e}^-}$
- $\boldsymbol{\textbf{O} + 2\textbf{e}^- \rightarrow \textbf{O}^{2-}}$

This results in the formation of magnesium oxide ( $\boldsymbol{\textbf{MgO}}$ ), a compound used in refractory materials for high-temperature applications.

Amphoteric Nature of Certain Metal Oxides

Some metal oxides, like aluminum oxide ( $\boldsymbol{\textbf{Al}_2\textbf{O}_3}}$ ) and zinc oxide ( $\boldsymbol{\textbf{ZnO}}$ ), exhibit both acidic and basic properties. They react with both acids and bases to form salts and water. These oxides are called amphoteric oxides.

Example:

Aluminum oxide ( $\boldsymbol{\textbf{Al}_2\textbf{O}_3}$ ) reacts with hydrochloric acid ( $\boldsymbol{\textbf{Al}}$ ) to form aluminum chloride ( $\boldsymbol{\textbf{AlCl}_3}}$ ) and water:
- $\boldsymbol{\textbf{Al}_2\textbf{O}_3 + 6\textbf{HCl} \rightarrow 2\textbf{AlCl}_3 + 3\textbf{H}_2\textbf{O}}$

It also reacts with sodium hydroxide ( $\boldsymbol{\textbf{NaOH}}$ ) to form sodium aluminate ( $\boldsymbol{\textbf{NaAlO}_2}}$ ) and water:
- $\boldsymbol{\textbf{Al}_2\textbf{O}_3 + 2\textbf{NaOH} \rightarrow 2\textbf{NaAlO}_2 + \textbf{H}_2\textbf{O}}$

Real-life Application:

Aluminum Oxide in Ceramics: Aluminum oxide is used in the production of ceramics and refractory materials due to its high melting point and resistance to chemical attack.

Practice Questions with Answers

Q1: What type of bond is formed between sodium and chlorine in sodium chloride ( $\boldsymbol{\textbf{NaCl}}$ )?

Answer: An ionic bond is formed between sodium and chlorine, where sodium donates one electron to chlorine.

Q2: Explain why magnesium reacts with oxygen to form magnesium oxide ( $\boldsymbol{\textbf{MgO}}$ ).

Answer: Magnesium loses two electrons to form a $\boldsymbol{\textbf{Mg}^{2+}}$ ion, and oxygen gains two electrons to form an $\boldsymbol{\textbf{O}^{2-}}$ ion. The electrostatic attraction between these oppositely charged ions results in the formation of magnesium oxide.

Q3: How does aluminum oxide exhibit amphoteric behavior?

Answer: Aluminum oxide reacts with both acids (to form salts like aluminum chloride) and bases (to form sodium aluminate), showing its amphoteric nature.