Halogens have been placed in the VII group of the peri- odic table because they are/have

Options

A. non-metals
B. very reactive
C. electronegative
D. seven electrons in outermost orbit

Answer

To answer the question of why halogens are placed in the VII group of the periodic table, we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Identify Halogens**:
- Halogens are a group of elements that include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

2. **Group Number**:
- Halogens are placed in Group 17 (or VIIA in older nomenclature) of the periodic table.

3. **Electron Configuration**:
- The outermost electronic configuration of halogens is characterized by having seven electrons in their outer shell. This can be represented as \( ns^2 np^5 \), where \( n \) is the principal quantum number corresponding to the period of the element.

4. **Reason for Group Placement**:
- The reason they are placed in Group 17 is that they have a total of 7 valence electrons. This configuration makes them very reactive, as they tend to gain one electron to achieve a stable octet configuration.

5. **Properties of Halogens**:
- Halogens are known to be non-metals, highly electronegative, and reactive. Their reactivity increases as you move up the group, with fluorine being the most reactive and electronegative element in the periodic table.

6. **Size and Reactivity**:
- As you move down the group from fluorine to astatine, the atomic size increases due to the addition of electron shells. This increase in size affects their reactivity and electronegativity.

7. **Conclusion**:
- In summary, halogens are placed in Group 17 of the periodic table because they have 7 electrons in their outermost shell, which defines their chemical properties and reactivity.

### Final Answer:
Halogens have been placed in the VII group of the periodic table because they have 7 electrons in their outermost shell (valence shell), which corresponds to their electron configuration of \( ns^2 np^5 \).

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