KETERAMPILAN PROSES SAINS PADA PRAKTIKUM IPA MATERI ASAM BASA PADA MAHASISWA PGMI IAIN PALU

The purpose of this study was to describe the science process skills of  students of  PGMI FTIK IAIN Palu on the science  laboratory of Asam Basa. This research is a descriptive study conducted at the PGMI Study Program in September to October 2019. The research subjects were students of semester 3 of PGMI in the academic year 2019/2020 who took 28 natural science courses. Data in the form of students' Science Process Skills were obtained from the student performance appraisal in the science practicum on acid-base material. The results showed that students' science process skills varied in each category. For the category of skills using tools and materials, the average percentage for the 2 indicators is 83.05% or very high. For the category of observation skills, the average percentage for the two indicators is 83% or very high. For the grouping / classification skills category, the average percentage for the 2 indicators is 79% or in the high category. Whereas for communication skills where in this category there are 3 indicators with an average indicator of 82.5 or very high. Overall by averaging the percentage of all indicators obtained the percentage for science process skills in science lab, wet acid material is 82%. This shows that the science process skills of PGMI students are very high.

Structural, Electronic and Vibrational Properties of 2Nd Row Transition Metal Clusters

Metal clusters play key role in chemical industry, nanotechnology and cellular biology. Chemical industry depends on the selection, development and application of catalysts. The most valuable catalysts used in these modern chemical industries consist of metal clusters. Introduction of a dopant atom in a metal cluster significantly enhances the catalytic activity. Moreover, in heterogeneous catalysis, the ability of metal cluster to react chemically with different molecular species totally depends on the size of the clusters. Bimetallic nano clusters have gained significant interest due to their specific and matchless structural, optical, electronic, and magnetic properties and their significance in nano technology and catalysis. Full range of bimetallic silver-yttrium AgnYm cluster of low nuclearity (n + m = 2-10) are studied using the density functional theory (DFT) at TPSSTPSS method with a Lanl2dz pseudopotential. The results for various properties including structural, ionization potential adiabetic, electron affinity, binding energy, HOMO-LUMO gap, average bond length, total energy, bond dissociation energy and 2nd order difference energy are evaluated as function of (n+m) size of the system. Moreover, the results for these bimetallic clusters are compared with pure silver and yttrium clusters. Different spin multiplicities of each cluster are also studied to locate the low energy structures. Cluster with higher nuclearity (n + m ≥7) favors three dimensional structure where clusters with low nuclearity (m + n ≤6) except (n + m = 5) favor two dimensional structure. Ag6 cluster also preferred planar 2D configuration. All pure silver clusters are more stable in low spin multiplicity, while pure yttrium clusters are more stable in higher spin multiplicity. Multiple bimetallic silver yttrium clusters have stability at varying spin state. Based on binding energy values the pure yttrium clusters are more stable than pure silver and bimetallic clusters. Density functional theory calculations have also been performed on pure silver (Agn), yttrium (Ym) and bimetallic silver yttrium clusters AgnYm (n+m = 2-10) for reactivity descriptors in order to find active sites for electrophilic and nucleophilic attack. The results illustrates that atoms in a stable ground state in a geometry can be categorized into different types of reactive sites. The reactivity of numerous sites as a function of cluster size and shape was thus investigated. The investigation reveals that the sizes and shapes of the pure silver, yttrium and bimetallic silver yttrium cluster (n = 2-10) influence the number and position of active sites for an electrophilic and/or nucleophilic attack. Doping of pure clusters with the other elements also influences the hardness, softness and chemical reactivity of the clusters. The softness increases as we increase the number of silver atoms in the cluster, whereas the hardness decreases. The chemical reactivity increases with silver doping whereas it decreases by yttrium doping. Silver atoms are nucleophilic in small clusters whereas, in large clusters, silver atoms are electrophilic in nature. The research here is designed at the investigation of new bimetallic clusters with distinctive electronic properties. These distinctive electronic properties comfort in finding new applications in electronic devices. Furthermore, these silver yttrium bimetallic clusters are expected to have improved catalytic activity which will assist industrial processes.