On going from right to left in a period in the periodic table the electronegativity of the elements:

Options

A. Increases
B. Decreases
C. Remain unchanged
D. Decreases first then increases

Answer

To answer the question regarding the trend of electronegativity when moving from right to left in a period of the periodic table, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Electronegativity**:
- Electronegativity is defined as the ability of an atom to attract shared electrons in a chemical bond.

2. **Periodic Trends**:
- In the periodic table, electronegativity generally increases from left to right across a period. This is due to an increase in the effective nuclear charge (Z_eff) experienced by the outermost electrons.

3. **Effective Nuclear Charge (Z_eff)**:
- Z_eff is the net positive charge experienced by valence electrons. As we move from left to right in a period, protons are added to the nucleus, which increases the positive charge and thus increases the Z_eff.

4. **Impact on Electronegativity**:
- As Z_eff increases, the nucleus exerts a stronger pull on the outermost electrons, making it easier for the atom to attract electrons from other atoms. Therefore, electronegativity increases.

5. **Direction of Movement**:
- The question asks about the trend when moving from right to left. Since we established that electronegativity increases from left to right, it follows that it must decrease when moving from right to left.

6. **Conclusion**:
- Therefore, as we move from right to left in a period, the electronegativity of the elements decreases.

### Final Answer:
The electronegativity of the elements decreases when going from right to left in a period in the periodic table.