Electronegativity is increases in a group from top to bottom
vertically because the atomic size of the elements is increases for
higher atomic masses .
for example, 17th group elements, F -
4.0Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
                                                         Â
Cl - 3.0
                                                         Â
Br - 2.8
                                                         Â
I - 2.5
Electronegativity is decreases in a period from left to right
hoizontally because the atomic size of the elements is decreases
for higher atomic masses.
for example 2nd period elements, Â
Li-1.0, Be-1.5, B-2.0, C-2.5, N-3.0, O-3.5, F-4.0.
