Question

Which of the following has the least electron affinity?

• A. $Na$
• B. $Ca$
• C. $K$
• D. $F$

Answer 1

The correct option is A $Na$

• The electron affinity of an atom or molecule is defined as the amount of energy released or spent when an electron is added to a neutral atom or molecule in the gaseous state to form a negative ion.
  
• The less valence electrons an atom has, the least likely it will gain electrons. Electron affinity decreases down the groups and from right to left across the periods on the periodic table because the electrons are placed in a higher energy level far from the nucleus, thus a decrease from its pull.
  
• Considering the trends we find $Na$ will be having least electron affinity as $Na$ readily looses its electron to form stable $N{a}^{+}$.