When comparing the electronegativity of calcium and gallium, gallium has the greater electronegativity. This can be understood by considering the position of both elements in the periodic table.
Calcium is an alkaline earth metal located in group 2, while gallium is a post-transition metal found in group 13. In general, electronegativity tends to increase as you move from left to right across a period and decrease as you move down a group. This trend is due to the increasing positive charge of the nucleus, which more effectively attracts the bonding pair of electrons.
Calcium, being further to the left, has a lower electronegativity because it is more likely to lose its outer electrons and form cations. In contrast, gallium, with its higher position in the periodic table and additional protons, attracts electrons more strongly, leading to a higher electronegativity.
According to the Pauling scale, the electronegativity of gallium is approximately 1.81, whereas that of calcium is around 1.00. This significant difference illustrates that gallium is better at attracting electrons when forming bonds.