Representing human knowledge plays an important role in artificial intelligence science. Nowadays, there are many effective methods for representing knowledge such as semantic networks, conceptual graphs, computational networks. Computational Objects Knowledge Base (COKB) can be used to represent knowledge in many kinds of knowledge domain, such as Linear Algebra, Analytic Geometry, Direct Current Electrical Circuits. However, COKB model cannot be used to represent knowledge and solve problems about chemical elements efficiently. In this paper, we propose a variation of COKB model called Che-COKB which is the useful tool to represent knowledge about chemical elements and solve some kinds of problems in this knowledge domain. Furthermore, the algorithms for solving problems on model have been built up. In addition, the proposed model and algorithms were also applied to construct an application for solving some problems about chemical elements on mobile devices.