MCQ Detailed View

Electronegativity is defined as the ability of an atom to attract electrons towards itself in a chemical bond. It is a fundamental property of elements and is influenced by factors such as nuclear charge, atomic size, and electron shielding effect.

Across a period of the periodic table (from left to right), electronegativity increases. This trend occurs because:

1️⃣ Increase in Nuclear Charge:
As we move from left to right across a period, the number of protons in the nucleus increases. This results in a stronger positive charge that attracts electrons more strongly towards the nucleus.

2️⃣ Decrease in Atomic Radius:
Although additional electrons are added in the same principal energy level, the increasing nuclear charge pulls the electron cloud closer to the nucleus. This reduces the atomic size, increasing the effective nuclear pull on bonding electrons.

3️⃣ Shielding Effect Remains Constant:
Electrons are added in the same shell across a period, so the shielding effect does not increase significantly. Hence, the attraction of the nucleus on the valence electrons becomes stronger.

Due to these combined effects, nonmetals on the right side of the periodic table (e.g., fluorine, oxygen, nitrogen) have the highest electronegativity values, while metals on the left (e.g., sodium, magnesium) have lower values. Fluorine is the most electronegative element with a value of approximately 3.98 on the Pauling scale.

Incorrect options:

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  Decrease: This happens down a group, not across a period.

  
  


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  Constant: Electronegativity changes significantly, so it is not constant.

  
  


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  None of these: Not correct because we know the trend is increasing.

  
  

Therefore, the correct answer is Option 1 (Increase) as electronegativity increases from left to right across a period in the periodic table.