Question

Which is an active metal?

Answer 1

An **active metal** is a metal that readily reacts with other substances, particularly water, acids, and oxygen. Active metals tend to lose electrons easily, making them good reducing agents. These metals are typically located in the first two groups (Group 1: Alkali Metals and Group 2: Alkaline Earth Metals) of the periodic table.

### Characteristics of Active Metals:
1. **High Reactivity**: Active metals react vigorously, especially with water and acids, releasing hydrogen gas.
2. **Low Ionization Energy**: They require less energy to lose their outermost electrons.
3. **Form Basic Oxides**: Their oxides are often strongly basic and react with water to form hydroxides.

### Examples of Active Metals:
1. **Alkali Metals (Group 1)**:
   - **Lithium (Li)**, **Sodium (Na)**, **Potassium (K)**, **Rubidium (Rb)**, **Cesium (Cs)**
   - React vigorously with water to form hydroxides and hydrogen gas:
     \[
     2 \, \text{Na} + 2 \, \text{H}_2\text{O} \rightarrow 2 \, \text{NaOH} + \text{H}_2
     \]

2. **Alkaline Earth Metals (Group 2)**:
   - **Magnesium (Mg)**, **Calcium (Ca)**, **Strontium (Sr)**, **Barium (Ba)**
   - React with water (though less vigorously than alkali metals):
     \[
     \text{Ca} + 2 \, \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + \text{H}_2
     \]

3. **Other Examples**:
   - Aluminum (Al) is reactive but forms a protective oxide layer that slows further reaction.
   - Zinc (Zn) and Iron (Fe) are moderately active and react with acids to release hydrogen.

### Inert vs. Active Metals:
- **Inert metals** like gold (Au), platinum (Pt), and silver (Ag) are unreactive due to their high ionization energies and reluctance to lose electrons.
- **Active metals**, by contrast, have low ionization energies and react readily.

Among these, the alkali metals like sodium and potassium are the most reactive and are often cited as prime examples of active metals.