Justify the given statement with suitable examples -"the properties of the elements are a periodic function of their atomic numbers"?

Explanation

To justify the statement "the properties of the elements are a periodic function of their atomic numbers," we can follow these steps:

### Step 1: Understanding Periodicity
The periodicity of elements refers to the recurring trends in their properties when arranged by increasing atomic number. This is based on the periodic law, which states that the properties of elements are a periodic function of their atomic numbers.

### Step 2: Grouping Elements
Let's consider elements from specific groups in the periodic table. For example, we can take Group 1 elements, which include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

### Step 3: Electronic Configuration
Each of these elements has a similar outer electronic configuration:
- Lithium (Li): 1s² 2s¹
- Sodium (Na): 1s² 2s² 2p⁶ 3s¹
- Potassium (K): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
- Rubidium (Rb): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 4p⁶ 5s¹
- Cesium (Cs): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 4p⁶ 5s² 5p⁶ 6s¹
- Francium (Fr): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 4p⁶ 5s² 5p⁶ 6s² 6p⁶ 7s¹

The general electronic configuration for Group 1 elements is ns¹, where n represents the period number.

### Step 4: Similar Properties
Due to their similar outer electronic configuration, these elements exhibit similar chemical and physical properties:
- They are all soft metals.
- They are highly reactive, especially with water.
- They all form +1 ions (Li⁺, Na⁺, K⁺, etc.).

### Step 5: Comparison with Other Groups
We can also look at Group 2 (alkaline earth metals) and Group 17 (halogens):
- Group 2 elements (Be, Mg, Ca, Sr, Ba, Ra) have the general electronic configuration ns² and form +2 ions.
- Group 17 elements (F, Cl, Br, I, At) have the general electronic configuration ns² np⁵ and typically form -1 ions.

### Step 6: Conclusion
The periodicity in properties is a result of the repeating nature of electronic configurations as we move across the periodic table. As we increase the atomic number, we observe that after a certain interval (like 8 for alkali metals), the properties of the elements repeat due to their similar electronic configurations.