Alkali metals in each period have

Options

A. Smallest size
B. Highest `EN`
C. Lowest `IE`
D. Highest `IE`

Answer

To answer the question regarding the properties of alkali metals in each period, we will analyze the characteristics of alkali metals based on size, ionization energy, and electronegativity.

### Step-by-Step Solution:

1. **Understanding Alkali Metals**:
- Alkali metals belong to Group 1 of the periodic table. This group includes elements like lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

2. **Size of Alkali Metals**:
- As we move down the group from lithium to francium, the size of alkali metals increases. This is due to the addition of electron shells, which outweighs the increase in nuclear charge.
- In terms of comparison across periods, alkali metals have a larger atomic size compared to elements in the same period but smaller than the noble gases in the subsequent period.

3. **Ionization Energy**:
- Ionization energy is the energy required to remove an electron from an atom. For alkali metals, this energy is low because they have only one electron in their outermost shell.
- As we move down the group, the ionization energy decreases because the outermost electron is further from the nucleus and is shielded by inner electrons.

4. **Electronegativity**:
- Electronegativity is the tendency of an atom to attract electrons. Alkali metals have low electronegativity because they readily lose their single valence electron to achieve a stable electron configuration.
- Therefore, alkali metals are characterized by high electropositivity rather than electronegativity.

5. **Conclusion**:
- From the analysis above, we can conclude that alkali metals have the lowest ionization energy compared to other groups in the periodic table. They do not have the smallest size or highest electronegativity.

### Final Answer:
Alkali metals in each period have the **lowest ionization energy**.