A consistent set of atomic electronegativities of main block and d-block transition elements has been obtained from the position and value of the molecular electrostatic potential bond critical point of the C-E bond of a methyl-element-hydride system, H3C-EHn (E is an element and n = 0, 1, 2, 3, 4, and 5 depending on the position of E in the periodic table). The new scale shows very good agreement with the popular electronegativity scales such as Pauling, Allen, Allred-Rochow, Mulliken, and Sanderson scales of electronegativity, especially for the main block elements. The present scale of electronegativity for transition elements is expected to be more accurate than the previously derived values because of a more consistent approach. Further, the same approach has led to the evaluation of group electronegativities when the hydrogens of E are replaced by other substituent groups. These group electronegativity values are found to correlate well with Inamoto and Mullay scales.