The crossword solution for the term 'prefix with valence' is AMBI. This prefix is derived from the Latin word 'ambi', which means 'BOTH'. It is used to denote a state of having two opposite qualities or elements, such as positive and negative. For example, an ambivalent emotion is one that contains BOTH positive and negative feelings. In chemistry, the term 'valence' refers to the number of electrons in an atom's outermost shell, which determines its reactivity. Therefore, when the prefix 'ambi' is combined with 'valence', it indicates a state of having two different valences.