In this work, we propose a conceptual model for existential events that affect portions of matter. Portions of matter are entities that constitute most of the physical entities, for instance, water, oil, gold, and blood. Existential events create and destroy entities. The proposed conceptual model is intended to support the design of information systems that capture the dynamic changes of portions of matter in nature and industrial processes. First, we propose a taxonomy for Collections of Objects (the entities that constitute portions of matter) and define the phase transitions that create and terminate the circumstances for a portion of matter to exist. Second, we define three existential events that affect portions of matter: (i) Forming Stuff, in which an instance of portion of matter is created as a collection of objects become connected; (ii) Terminating Stuff, in which an instance of portion of matter is terminated as a collection of granules become scattered; (iii) Changing Stuff Type, where a quantity of one kind is created and a quantity of another kind is terminated.
Lastly, we present an application example that uses the condensation of a portion of water and its freezing into a portion of ice to illustrate how to use the conceptual model in concrete cases.
