Alex, Maria, Gage, Frankie
Electronegativity increases as you go from left to right on the periodic table. This happens because as you increase from left to right the number of valence electrons increases, meaning they will not have as much need to give electrons away as elements on the left side.
Elements with 1-2 valence electrons would rather give them away to achieve an octet in a lower energy level. Meaning that they would rather give away 1-2 rather than take in 6-7 electrons.
Electronegativity decreases as you go down a group in the periodic table. Elements near the bottom have more electrons, so they are less reactive than those with fewer electrons at the top of the table.
Due to shielding, for elements that are closer to the top where there are fewer electrons, every electron is important so they have a stronger need to obtain more. Near the bottom the elements have more electrons, so if they lose an electron, it is not of major importance.