Writing Chemical Formulas Don Ross, Microcomputer Workshops, 225 Westchester Street, Port Chester, NY 10573
Hardware: Apple II family Components: 1 program disk. 1 backup disk.
teacher's manual Level and Subject: Grades 7-12, introdue tory chemistry cost: $34.95
The stated objectives of the program are to give students practice in writing chemical formulas and to facilitate the understanding of the balancing of positive and negative charges in a chemical formula. Problems are generated randomly from a list of 11metals and 11 nonmetals, giving a possible comhination of 121 different formulas. Subscripts and upper and lower symbols are used in all formulas (as well as parentheses where appropriate). The student may see a list of all the elements, their symbols and oxidation states at any time by pressing the "*" key. The student is asked to enter the correct formula of a comnonnd. If unable to do so. thecomputer will;espond"~o you needan" help'?" Appropriate hrlp is giwn if the answer is affirmative. At the end of each pnrhlem, the number of errors made is shown. The student can then either try another problem or exit the program. If the student decides to exit the program, the number of problems attempted, the total errors, and the average number of errors per problem are given. The instructions for use of the program are contained d t h i n the program itself, They are very clear and well written without being excessively wordy. Because the table of common ions is available to the students during the program, they do not need to bring any materials with them. The user can operate this program very easily without any computer experience. The input prompts are easy to understand and the program does not leave the user stranded if an incorrect input is made. One very nice aspect of the program is that the user is able to type subscripts in formulas by typing the "esc" key first. Subscripts make the formulas more realistic and are just one example of the thoughtful programming
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that was done here. In fact, the program prompts the user as to what is expected if a mistake is made. I sometimes got an 110 error when warm booting the program, which may be due in part to the copy protection scheme used in this software. This well-written program cannot be modified by theinstructor. The programassumes that thestudent is somewhat familiar with writing the symbols for the elements and has had the concept of the least common multiple in a math course. The program meets its objectives quite well. The pedagogic approach of drill and practice is very appropriate for the subject of writing chemical formulas. The program takes the user through the problem step by step when a mistake is made. I t would be better if the program gave a series of five prohlems before asking if the user would like to continue, however, rather than asking after each problem. I found that some of mv students would auit after doine a coude of pnhlems, thinking they knew the material, when actualiv 1ht.y had not experienced somr of the more difficult aspects of formula writing, such as the use of parentheses. I have found that if there is a stumbling block to ionic formula writing it is understanding the use and meaning of parentheses in formulas. I was glad to see that this program does give the student some practice in this area. The program would probably be most appropriate at the middle school science Level. I have found that writing ionic formulas is not a particularly difficult concept tomaster for even the poorest of high sehwl chemistry students. I had difficulty finding students who had a ledtimate need to test the program for me. Moct of my test students Were those that were finished with their classwork for theday and had thetime totry the program. They caught on quickly (even
if I had not covered the topic in class yet) and rapidly became bored. The value of this well-written program is diminished because the topic can be covered efficiently and completely without the use of a computer. The method of instruction is exactly the same as the one I use in mv chemistnr classes. The main value of the program is therefore in the areas ofenrichment and remediation. The program Seems most useful for students who rither need extra practice at writing ionic formulas brcause they did not "catch on" during the regular classwork or for students who may have been absent when the tooic was covered in class and need to learn it for the first lime. The program might also be appropriate for students who excel at their regular classwork and want to work independently a t a faster pace than the rest of the class. My students ran this program with no assistance whatsoever from me. The student reaction was that if they had already had some instruction in writine chemical formulas thev were finished with the program after doing only a few problems. If the student had not had instruction, the program did a good job of quickly getting the material across. My reaction is that I wish I had software that was as well written as this covering some of the more difficult concepts of first-year chemistrv such as stoichiometrv. ..dimensional analysis, 1,alanring oxidation-reduction equations, gas law*, etc. I'rograms in thcse areas would be a time-sarrr for me and a benefit to students In summary, this is an easy-to-use, wellwritten, productive program. My only suggestions for im~rovementare that the stu&nts be given series of problems to solve before being asked if they would like to eontinue. Also, the list of ions used to make up
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Summary Ratings: Revbwer
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d In This Issue
Computef Learning Package
Reviewer
Don Ross, Writing Chemical Formulas
Joseph M. Pavlovich Kathleen SweeneyHammond
A88
Carl J. Sindermann, Winning the Games Scientists Play
George B. Kauffman
A9 1
Ira N. Levine, Physical Chemistry, Second Edition
Thomas G. Dunne
A9 1
Books
A88
Journal of Chemical Education
the practice problems should be more comprehensive. I found that the program was not particularly useful t o me in high school chemistry because the concept taught is not particularly difficult, b u t t h e program might he useful in other areas of secondary or middle school science. Joseph M. Pavlovich Flint NorHnern High School 6 3 2 8 4 Mackin Road Flint, MI 48504 Revlew II This program provides a basic drill and tuturial prurram for learning huw 10 write chrmicsl f o r m ~ l a iThe . program randomly ~ I I O V S Cromvound ~~ irum a list uf 11 metals and 11 nonm&ls. The compounds formed are all ionic and none are included which have multiple valences. The program automatically keeps track of the number of errors committed on each formula and allows students t o get tutorial help along the way if they are unahle to figure out a formula. There is only one program on the disk and it automatically loads. The directions are simple and a student needs only t o know how to load a disk and turn the computer on and off t o work with i t effectively. The only problem with input is the need to press the escape key every time a lower-case letter is required. My students found this annoying and a cause of numerous mistakes in their answers.
The pmgmm isnimrd at nwrnyr to hclow cvrra:r srudmrs. I t ~ s w drhc program with eighth graders in an introductory chemistry course and 10th and 11th graders in Chem Study. There is very little classroom prep time necessary t o use the program. My students needed t o have a hrief introduction on how a compound was named (positive ion first, negative ion second, binary end in -ide). The pragram includes only ionic eompounds and hence only the concept that the sum of all charges must equal zero needed to he introduced. The program provides a useful feature for beginning students; the table of 22 ions can he called up with one stroke whenever a student forgets a formula or the charge on an ion. My eighth graders found that it made the pragram very beneficial for them. In my experience the program became too simplistic after one time through far my Chem Study students. I t clearly explains how to determine the number of times each ion appears in a compound by finding the least eomman multiole of the charms: .. . howe w r . for my high whcad arudenLz thnr iz nor thr pnhlem. Their problem comes in thew inability to memorize the charges on the ions and their failure to deal properly with ions having more than one oxidation numher. This program does not make any attempt to deal with this type of problem. My students liked the pragram hut began askine for harder ~ r o b l e m safter the" had used it ~ u s once, t and I could mor mudif? rhs prw gram tu add mure mni althmgh 1 could ger the program t u lrst. The malg,r prahlem wlrh the pragram is that it does not aceommodate the various ability levels of students. I t is designed specifically for the student who
has trouble with the concept of balancing charges. The eighth graders, however, loved using the program and found it re-enforced the lesson I had gone over in class. I t allowed students who were unahle to grasp the concept of lowest common multiple to struggle with it slowly and quietly instead of asking questions in class in front of their quicker peers. I found it helped these students enormously andgave them the self confidence to ask questions in class. Those students who used the program did significantly better on quizzes. The tutorial sections are clear and will provide the answer if the student is unable to put in the correct information after one try. If a student answers with an incorrect formula the program asks if the student wants help. The program displays a box that will hold the information the student inserts about each ion. If the student asks for help the pragram asks for the formula of the positive ion, then the charge on the positive ion. It then requests the same information about the negative ion. The program asks the student to find the lowest eomman multiple and the numher of each ion needed t o get this number. If the student answers incorrectly, the program branches to a tutorial on how to find the LCM and how the LCM relates to the formula. The program then asks the student t o try t o determine the formula wain. If the student cannot do this thp infmnnr~onnecrsmry is highlighr~don the wrern and the sttrdmt is gwen nnurher chance. If r h answer ~ is srdl mccmert, rhe student is given the correct answer. My students found it annoying after the first few times on the program that they had to go
