Proceeding of Chemistry Conferences vol. 1 2016 ISSN 2541-108X
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between the two oxygen-hydrogen bonds is approximately 104.5°, which is slightly smaller than the angle typically found in tetrahedral-shaped molecules. This is due to the particularly strong repulsions by the
lone-pair electrons on the oxygen atom, which pushes the hydrogens closer together than usual. Due to the same reason, the NH
3
geometry could not be fitted in planar shape. Meanwhile, the CO
2
structure is suited in linear geometry since no lone pair electron owned by a carbon atom.
Figure 6. The representation of the changing of molecular geometries of three of simple molecules, H
2
O, CO
2
, and NH
3
.
6. Summary
One of the appropriate and simple 3D model, the
origami
technique for visualising the molecular shape method is a ‗hands-on‘ approach in building molecules expected more intention while gaining the building
experiences. The present technique is simple, readily accessible and inexpensive compared with other sophisticated methods such as computer modellingsimulation and three-dimensional expensive
commercial model kits. This method can be implemented in chemical education both at high school and university level studies. Applying the
origami
technique at the beginning of the molecular shape study, the students not only might predict the molecular shape but also could understand the reason for the change at
the beginning of their study. Furthermore, they might directly describe the molecular shape in 2D drawing without doubtful with full understanding.
Acknowledgment This work was supported in part by Grants of PNBP 2015-2016 in the scheme of
Hibah Ipteks bagi Masyarakat
and Grant of Maintenance Research Group from Sebelas Maret University
Proceeding of Chemistry Conferences vol. 1 2016 ISSN 2541-108X
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References [1]
Rayner-Canham, G. and Overton, T. 2010 Descriptive Inorganic Chemistry, W. H. Freemen and Company, USA.
[2] Housecroft, C. E. and Sharpe, A. G. 2005 Inorganic Chemistry, 2
nd
edition, Ashford Colour Press Ltd., Gosport, England.
[3] Mȕller, U. 2006 Inorganic structural chemistry, 5
th
edition, John wiley Sons Inc., USA [4]
Mitchell, D. 2005, Mathematical
origami
, Tarquin Publications, St Albans, UK. [5]
Davis, J. 2010
Origami
: a versatile modelling system for visualising chemical structure and exploring molecular function, Chem. Educ. Res. Pract., 11, 43-47.
[6] Hanson, Robert M. 1995 Molecular
Origami
: Precision Scale Models from Paper. University Science Book. USA.
[7] http:employees.oneonta.eduviningwjchem111molecular20geometries.jpg [accessed on Sept 8,
2015]
Proceeding of Chemistry Conferences vol. 1 2016 ISSN 2541-108X
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Development Performance Assessment Instrument with Estimating the Reliability Using Generalizability Theory
E Susilaningsih, S N Suwaibah and Sudarmin
Chemistry Department Matematics and Natural Sciences Faculty Semarang State University
E-mail: endang.arkanyahoo.com
Abstract. The aim of this research was to develop the performance assessment instrument of salt hydrolysis experiment on Senior High School with estimating the reliability used generalizability
theory. The subjects of this research consisted of 35 students of Islamic Senior High School 1 Semarang. In this research pre-experimental one shoot case study was used. The stages of this
research are need analysis, design instrument, validation and testing. The data analyzed by using quantitative descriptive analysis and the reliability estimated by using generalizability theory. Two-
facet crossed G-study and D-study design were used where three rater graded 13 item student performance. Results of analyses showed there was interrater reliability coefficient of performance
assessment was 0.717. The results showed instrument performance assessment on salt hydrolysis experiment were valid, reliable and practice.
1. Introduction The question
