The chemical behaviors of single-valence rock-forming elements, such as calcium, magnesium, and oxygen, are well-described by classical ionic bonding models under Earth surface and shallow mantle conditions. However, the extreme pressure-temperature (P-T) conditions prevailing within the deep lower mantle fundamentally alters the chemical behavior of these elements, potentially leading to the formation of superoxides like FeO₂ and CaO₃, characterized by oxygen oxidation states greater than -2. In this talk, we focus on the chemistry of calcium in the lower mantle. Using first-principles simulation, we report the emergence of multivalent calcium states, specifically Ca¹⁺ and Ca²⁺, within silicate and sulfide phases across depths spanning approximately 1200 km to the core-mantle boundary. We then identified the stabilization of Ca2SiO3, Ca4SiO3 and Ca2S, in which the ionic configuration of calcium is analogous to potassium. Further in-situ x-ray diffraction and Raman spectroscopy verified the formation of monovalent calcium compounds under the P-T conditions of lower mantle. These theoretical calculation and experiments introduce a series of heavy-calcium silicate and sulfide by pressure-engineering the outer shell electrons of calcium. The high densities of these phases suggest their gravitational stability within the lowermost mantle, potentially contributing to the formation of observed large-scale seismic structures and the development of chemical heterogeneities at the core-mantle boundary.