What term describes materials where the valence ring is partially filled?

The term that describes materials with a partially filled valence ring is "reactive." When the outermost electron shell of an atom is not completely filled, the atom has a tendency to interact with other atoms in order to achieve a more stable electron configuration. This can involve gaining, losing, or sharing electrons.

For instance, elements such as those in Groups 1, 2, and 13 of the periodic table have incomplete valence shells and are more likely to react with other elements to fill their shells. This reactivity is a fundamental concept in chemistry, indicating that these materials will readily participate in chemical reactions.

The other terms mentioned do not accurately describe materials with partially filled valence rings. "Stable" refers to systems that do not readily react; "inert" typically describes noble gases that have completely filled valence rings and are therefore non-reactive; and "fixed" is a term that doesn't relate to electron configuration in this context. Hence, the understanding of reactivity is key in determining the behavior of these materials in chemical interactions.