The main objective of this study was to explore the effectiveness of using different particulate representations in chemistry on the explanations of second secondary science students in the Sultanate of Oman of chemical phenomena, and on the correction of their misconceptions regarding these phenomena. The sample included (120) students: (54) were males and (66) were females. They were distributed in two secondary schools in North Al-Batena Educational Administration. Two classes taught by one teacher from each school were chosen to participate in the study. Then one class in each school was chosen randomly to be as the experimental group and the other class as the control group. To inspect participants' mental abilities, Lawson's Test of Scientific Reasoning (Lawson, 1996) was administered to all groups before the beginning of the study. This test was translated into Arabic by the researcher, and then judged by four experts. Its reliability was measured by test-retest method, and the correlation coefficient was (.92). A chemical concepts test was designed by the researcher to measure. participants ability to explain different chemical phenomena, and to explore their misconceptions regarding these phenomena. This test was judged by seven experts. Its reliability was measured by test-retest method, and the correlation coefficient was (.91). In order to measure the effectiveness of using particulate - representations, the chemical concepts test was used as a pre- and post-test. The Analysis of Covariance (ANCOVA) with students' scores from Lawson's Test of Scientific Reasoning as a covariant was used to compare between students in the experimental and control groups regarding their scores in the chemical concepts test. In addition, to measure the change occurred in both experimental groups over the course of the study, t-test for dependent groups was used to compare between students' scores in the pre- and post-tests. The results indicated that the particulate representations affected positively students' ability to explain chemical phenomena. Also, these representations corrected students' misconceptions regarding these phenomena. The experimental group scored significantly higher than the control group in the chemical concepts test, and students in the experimental group scored significantly higher in the post-test than the pre-test. On the other hand, there were no significant differences between the pre- and post tests of the control group. The results of this study recommend that the particulate representations should.. be used more frequently in school chemistry textbooks. Also, these texts should include exercises that train students to transfer different chemical equations, everyday observations, and laboratory results into particulate representations. This might improve students' imagination of the interactions among different atoms and molecules that permit the occurrence of chemical reactions and phenomena. In addition, the study recommends workshops which should be designed for chemistry teachers in order to train them in the use of the particulate representations, and to help them design different classroom activities for their students so that they can move easily among the three levels of chemistry (sensory, particulate, and symbolic).