To answer the question regarding the elements of the s-block, we will break down the information step by step.
### Step 1: Identify the Groups in the S-Block
The s-block of the periodic table consists of two groups:
- **Group 1 (Alkali Metals)**: Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), Francium (Fr).
- **Group 2 (Alkaline Earth Metals)**: Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), Radium (Ra).
**Hint**: Remember that the s-block includes both alkali and alkaline earth metals.
### Step 2: Determine Stability of Nuclei
- **Stable Nuclei**: Elements like Lithium (Li) and Beryllium (Be) have stable electronic configurations. Beryllium has a full outer s-orbital (1s², 2s²), which contributes to its stability.
**Hint**: Look for elements with complete electron shells for stability.
### Step 3: Identify Radioactive Elements
- **Unstable/Radioactive Nuclei**: In the s-block, elements like Francium (Fr), Radium (Ra), and Cesium (Cs) are known to be radioactive. These elements have unstable nuclei and can decay over time.
**Hint**: Radioactive elements often have higher atomic numbers and can be found at the bottom of the groups.
### Step 4: Assess Acidity and Basicity
- **Nature of Oxides**: S-block elements are metals, and their oxides are typically basic due to their electropositive nature. Therefore, they do not exhibit acidic behavior.
**Hint**: Metals generally form basic oxides, while non-metals form acidic oxides.
### Conclusion
- **Stable Nuclei**: Lithium and Beryllium.
- **Unstable/Radioactive Nuclei**: Francium, Radium, and Cesium.
- **Acidic Nature**: S-block elements are not acidic; they are basic.
### Final Answer
The s-block contains elements with stable nuclei (like Li and Be), unstable (radioactive) nuclei (like Cs, Fr, and Ra), and they are not acidic in nature, but rather basic.
