Among alkali metals which element do you expect to be least electronegative and why?

Explanation

To determine which alkali metal is the least electronegative, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Electronegativity**:
- Electronegativity is defined as the tendency of an atom to attract a bonding pair of electrons. It is a measure of how strongly an atom can attract electrons in a chemical bond.

2. **Identify Alkali Metals**:
- The alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

3. **Recognize the Trend in Electronegativity**:
- In the periodic table, electronegativity decreases as you move down a group. This is because the atomic size increases, which means that the bonding electrons are further away from the nucleus and are less attracted to it.

4. **Apply the Trend to Alkali Metals**:
- Since electronegativity decreases from top to bottom in a group, we can conclude that francium, being the heaviest alkali metal, will have the least electronegativity.

5. **Conclude the Answer**:
- Therefore, among alkali metals, francium (Fr) is expected to be the least electronegative element.

### Final Answer:
Francium (Fr) is the least electronegative alkali metal due to its position at the bottom of the group, where electronegativity decreases as atomic size increases.

---