Which term refers to how strongly an atom of an element attracts electrons in a chemical bond with an atom of a different element?
(1) entropy
(2) electronegativity
(3) activation energy
(4) first ionization energy

Answer is: (2) electronegativity.

Electronegativity (χ) is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.  

Atoms with higher electronegativity attracts more electrons towards it, electrons are closer to that atom.  

For example, in ionic salt lithium fluoride (LiF), fluorine has electronegativity approximately χ = 4 and lithium χ = 1 (Δχ = 4 - 1; Δχ = 3), fluorine attracts electron and it has negative charge and lithium has positive charge.

the answer would be a