Final answer:
The valence of antimony in antimony trichloride is 3⁺.
Step-by-step explanation:
The valence of antimony in antimony trichloride (SbCl₃) is 3⁺.
Valence is the number of electrons that an atom gains or loses in order to achieve a stable electron configuration. In this case, antimony (Sb) is in Group 15 of the periodic table and has an electronic configuration of [Kr]4d¹⁰5s²5p³. It needs to gain three electrons to achieve a stable electron configuration, so its valence is 3⁺.
The valence of antimony (Sb) in antimony trichloride (SbCl₃) is +3. This is because antimony forms a compound with chlorine where it shares three electrons, one with each chlorine atom, resulting in a trivalent (III) state. As per the provided information, antimony can react with halogens to form trihalides like SbCl₃ or, under certain conditions, pentahalides like SbCl₅ and SbF₅, indicating it can exhibit more than one oxidation state. In the case of antimony trichloride, antimony exhibits a +3 oxidation state, which is also reflected in the naming of the compound as antimony (III) chloride. Furthermore, the reaction of antimony with sulfur can result in either antimony(III) sulfide (Sb₂S₃) or antimony(V) sulfide, showing the adaptability in its valence.