This work derives electronegativity from first principles within Quarkbase Cosmology as an emergent, relational property of phase control in the Ψ-field. Without introducing chemical axioms, orbital postulates, or empirical fitting, electronegativity is shown to arise from nuclear phase rigidity and external-mode sensitivity. The framework naturally reproduces bond polarity, ionic and covalent limits, and periodic trends as consequences of resonance and phase coherence, providing a unified theoretical foundation for chemistry consistent with the Quarkbase Cosmology framework.