Determination of science student teachers' conceptions about ...

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Procedia Social and Behavioral Sciences 9 (2010) 1025–1029

WCLTA 2010

Determination of science student teachers’ conceptions about ionization energy Haluk Özmena * a

Karadeniz Technical University, Fatih Faculty of Education, Trabzon-TURKEY

Abstract Determination of preservice science teachers’ conceptions and alternative conceptions about ionization energy were aimed in this study. To achieve this aim, a two-tier multiple-choice test with ten questions was implemented to 300 preservice science teachers in their second and third year in Science Division of Fatih Faculty of Education at Karadeniz Technical University. The test was taken from literature. Researcher redesigned the original form of the test for the sample and the phrase “I do not know the answer” found in the first section of the original questions was extracted from the question for this study. Both first and second parts of the questions were analyzed and the percentages of students’ responses were calculated. Results showed that most of the preservice science teachers did not have an adequate understanding on ionization energy and had different alternative conceptions. © 2010 Published by Elsevier Ltd. Open access under CC BY-NC-ND license.

Keywords: Science student teacher, conception, alternative conception, ionization energy

1. Introduction Chemistry is a subject that is considered by many to be difficult for students (Chang & Chiu, 2005; Lorenzo, 2005; Taber & Coll, 2002). The reasons for this vary from the abstract nature of many chemical concepts to the difficulty of the language of chemistry (Ayas & Demirbaú, 1997). Taber and Coll (2002) note that the chemistry concepts are abstract in nature and require students to construct mental images of things they cannot see, and thereby find it hard to relate to. Another source of difficulty is that chemists describe chemistry at three levels and only one of which can be readily observed (Johnstone, 1999; Nelson, 1999; Tsaparlis, 1997). Numerous studies support the idea that the interplay between macroscopic and microscopic phenomena is a source of difficulty for many chemistry students. Researches show that such difficulties cause different students’ conceptions that are different from scientifically acceptable ones and may interfere with students’ learning of other scientific principles or concepts (Palmer, 1999). Such views are more commonly referred to as student alternative conceptions; that these views and ideas are logical, sensible, and valuable from the students’ point of view, even if they differ from accepted scientific views (Özmen, 2004; Pakua, Treagust & Waldrip, 2005). On the other hand, many researchers have reported that when fundamental concepts are not constructed adequately, more advanced concepts that build upon the fundamentals are not fully understood (Abraham, Grzybowski, Renner & Marek, 1992; Nakhleh, 1992). And also, these beliefs are widely held by learners in various grade levels, they are fairly pervasive, stable, and resistant to change by conventional teaching strategies and are often held intact by children and adults alike even after the completion of years of formal instruction (Guzzetti, 2000; Tsai, 1998; Wandersee et al., 1994). According 1877-0428 © 2010 Published by Elsevier Ltd. Open access under CC BY-NC-ND license. doi:10.1016/j.sbspro.2010.12.280

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to Niaz (2001), students’ preconceptions that resist changing can be considered as part of students’ “hard-core” beliefs. The concepts of electron, ionization energy, electronegativity, bonding, geometry, molecular structure, and stability are central to much of chemistry, from reactivity in organic chemistry to spectroscopy in analytical chemistry (Nicoll, 2001). It is also important for students to grasp these concepts in understanding why and how chemical bonds occur. Among these concepts, ionization energy is important for the understanding of atomic structure, periodic trends, and energetics of reactions (Taber, 2003; Tan, Treagust, Goh & Chia, 2005). But, it is a difficult topic for students to learn because it involves “abstract and formal explanations of invisible interactions between particles at a molecular level” (Carr, 1984, p. 97). On the other hand, conceptions of teachers and/or preservice teachers related to fundamental science concepts are important for school instruction. We generally know that how a teacher learns, he/she tends to teach such that. Therefore, if a teacher has alternative conceptions, he (she) probably transfers them to their students. This is because the importance of determination of teachers’ and/or preservice teachers’ conceptions. Moving from this idea, this study aims to determine preservice science teachers’ conceptions of ionization energy. 2. Methodology 2. 1. Sample The sample of the study consists of 300 preservice science teachers in their second and third year in Science Division of Fatih Faculty of Education at Karadeniz Technical University in Turkey. These student teachers took General Chemistry-I and General Chemistry-II courses in their first year. They took six hours course per week for each course. While four hours of the courses were theoretical, two hours were laboratory session. All of the student teachers studied the unit of chemical bonding and ionization energy. 2. 2. Instrument A two-tier multiple-choice test on ionization energy with ten questions was used to collect data. The test was taken from literature (Tan, Taber, Goh & Chia, 2005). The first tier of each item consists of a content question having two or three choices; the second part of each item contains three, four or five possible reasons for the answer given in the first tier response. These reasons include one scientifically acceptable answer and three alternative conceptions reported in the literature. Researcher translated and redesigned the original form of the test for the sample and the phrase “I do not know the answer” found in the first section of the original questions was extracted from the question for this study. One of the questions used in the study is given below. Q1. Once the outermost electron is removed from the sodium atom forming the sodium ion (Na+), the sodium ion will not combine with an electron to reform the sodium atom. A. True *B. False. Reason: (1) Sodium is strongly electropositive, so it only loses electrons. (2) The Na+ ion has a stable/noble gas configuration, so it will not gain an electron to lose its stability. *(3) The positively-charged Na+ ion can attract a negatively-charged electron. *: Correct response 2. 3. Data analysis Responses of the student teachers for both tiers of the questions were analyzed as percentages. And, because the second tier of the questions contained the possible alternative conceptions, these conceptions were also determined.

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3. Results and Discussion Preservice science teachers’ responses for the both tiers of the questions are given in Table 1. Table 1. Preservice science teachers’ responses fort he both tiers of the questions

Questions 1 2 3 4 5 6 7 8 9 10

Content A B A B A B A B C A B A B A B A B A B A B

(1) 7.3 1.6 9 9.6 15.6 2 22 2 8 2.3 20 9.3 1.3 3.3 7.6 4.6 9.6 4.3 8 16.3 13.6

(2) 33 3 7.3 6.3 7.6 7.6 23 1.3 1 9.3 9.3 19.6 9.3 9.3 7 6 31.6 9.3 4 9.3 8.3

Reason (%) (3) 3.6 34.6 45.6 5.3 6.6 2 13.3 1.6 2.3 5.3 10 8 9.3 4.6 5.3 12 8 31.6 7.3 8 13.6

(4) ----8 33.6 5 1.3 -5.3 8.6 7.6 6.3 20 9.3 4.3 4.6 5.3 6.6 3.3 8.6

(5) ---------8 4.6 7 4 2.3 10 --2 2 ---

Total (%) 43.9 39.2 61.9 21.2 37.8 45.2 63.3 6.2 11.3 30.2 52.5 51.5 30.2 39.5 39.2 26.9 53.8 52.5 27.9 36.9 44.1

Note: The correct responses are written in bold while alternative conceptions are written in italic.

As seen from the table 1, correct response combinations of the preservice science teachers vary from 2% to 34.6%. On the other hand, the ratio of their alternative conceptions is higher than the correct responses’ combinations. In some questions, they did not give response for the both tiers of the questions. The most common alternative conceptions are in the topics of octet rule, fully-filled or half-filled sub-shells, electron-nucleus attraction forces, change of ionization energies in the same period. Alternative conceptions determined in this study are given in Table 2. All of the alternative conceptions given below were taken from the literature without changing (Tan, Taber, Goh & Chia, 2005). In this study, author wanted to determine that how the sample of this study possessed these alternative conceptions. Table 2. Alternative conceptions of the preservice science teachers Choice combination Q1, (A2)

Percentage

- When an electron is removed from the sodium atom, the attraction of the nucleus for the ‘lost’ electron will be redistributed among the remaining electrons in the sodium ion.

Q2, (A3)

45.6

-

Because Na+(g) has a stable octet configuration, it is more stable than Na(g) atom

Q3, (B4)

33.6

-

The second ionization energy of sodium is higher than its first because the stable octet would be disrupted.

Q4, (A1)

22

-

The second ionization energy of sodium is greater than its first ionization energy because the same number of protons in the Na+ ion attracts one less electron, so the attraction for the remaining electrons is stronger.

Q4, (A2)

23

Alternative conceptions - The sodium ion will not recombine with an electron to reform the sodium atom, as its stable octet configuration would be disrupted.

33

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-

The first ionization energy of sodium is less than that of magnesium because magnesium has a fully filled 3s sub-shell.

Q5, (B1)

20

-

The first ionization energy of magnesium is greater than that of aluminum because the 3p electron of aluminum is further from the nucleus compared to the 3s electrons of magnesium

Q6, (A2)

19.6

-

The first ionization energy of sodium is greater than that of aluminum because the 3p electron of aluminum is further away from the nucleus compared to the 3s electron of sodium.

Q7, A(4)

20

-

The first ionization energy of silicon is less than that of phosphorus because the 3p sub-shell of phosphorus is half-filled.

Q8, (B2)

31.6

-

The first ionization energy of phosphorus is greater than that of sulfur because the 3p sub-shell of phosphorus is half-filled.

Q9, (A3)

31.6

-

The first ionization energy of silicon is greater than that of sulfur because it becomes half-filled only if an electron is removed from sulfur atom

Q10, (A1)

16.3

-

The first ionization energy of silicon is less than that of sulfur because it becomes half-filled only if an electron is removed from sulfur atom

Q10, (B1)

13.6

As seen from the table 2, twelve alternative conceptions were determined in the study and these alternative conceptions are the same as literature (Tan, Taber, Goh & Chia, 2005). The ratios of the alternative conceptions vary from 12% to 45.6%. These results show that preservice science teachers did not learn ionization energy and related concepts adequately. In the literature, it has been reported that students had difficulty in understanding the principles determining the magnitude of ionization energy (Taber, 1998, 1999, 2003). Students generally based their explanations on the octet rule and full shell framework. The abstract nature of the concept is the main source of the students’ difficulties. 4. Conclusion Students preexisting beliefs influence how students learn new scientific knowledge and play an essential role in subsequent learning (BouJaoude, 1991; Tsai, 1996). Hunt and Minstrell (1997) stated that children’s difficulties in science occur because students’ conceptions before teaching are not taken into account and therefore communication barriers between teachers and learners cannot be overcome. The results of this study show that preservice science teachers also have alternative conceptions related to ionization energy and related concepts. If teachers and/or preservice teachers have alternative conceptions, it is possible to say that their students will also have alternative conceptions. Therefore, it is extra important to determine teachers’ and/or preservice teachers’ alternative conceptions. On the other hand, altering these alternative conceptions to scientifically acceptable ones is as important as determining them. Based on the results of such studies, researchers, teachers, and teacher educators should develop new and alternative instructional techniques to alter and/or to prevent students’ alternative conceptions. References Abraham, M. R., Grzybowski, E. B., Renner, J. W. & Marek, E. A. (1992). Understandings and misunderstandings of eighth graders of five chemistry concepts found in textbooks. Journal of Research in Science Teaching, 29, 105–120. Ayas, A. & Demirbaú, A. (1997). Turkish secondary students’ conceptions of introductory chemistry concepts. Journal of Chemical Education, 74, 518–521. BouJaoude, S. B. (1991). A study of the nature of students’ understanding about the concept of burning. Journal of Research in Science Teaching, 28, 689–704. Carr, M. (1984). Model confusion in chemistry. Research in Science Education, 14, 97-103. 4


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