Write down the outermost electronc configuration of alkali metals. How will you justify their placement in group 1 of the periodic table?

Explanation

### Step-by-Step Text Solution:

1. **Identify Alkali Metals**: Alkali metals are the elements found in Group 1 of the periodic table. This group includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

2. **Determine Outermost Electron Configuration**: The outermost electronic configuration of alkali metals can be represented as \( ns^1 \), where \( n \) represents the principal quantum number. This means that there is one electron in the outermost s orbital.

3. **Justification for Placement in Group 1**:
- Alkali metals are characterized by having a single electron in their outermost shell (s orbital). This unique configuration leads to similar chemical properties among these elements.
- The presence of only one electron in the outermost shell makes them highly reactive, as they tend to lose that one electron easily to achieve a stable electronic configuration (like that of noble gases).
- The group number in the periodic table corresponds to the number of electrons in the outermost shell. Since alkali metals have one electron in their outermost shell, they are placed in Group 1.

4. **Comparison with Other Groups**: For comparison, elements in Group 2 (alkaline earth metals) have the outermost electronic configuration of \( ns^2 \), indicating they have two electrons in their outermost shell. This difference in the number of outer electrons justifies their placement in Group 2.

### Final Summary:
- The outermost electronic configuration of alkali metals is \( ns^1 \).
- They are placed in Group 1 of the periodic table due to having one electron in their outermost shell, which defines their chemical behavior and reactivity.

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