Shape of [SbF5]2-

Antimony, Sb, is in Group V of the Periodic Table so it has 5 valence electrons. Fluorine, from Group VII, only requires one electron through formation of 1 covalent bond to fulfill octet. Thus, all the 5 electrons of Sb are used to form covalent bonds with the 5 F atoms. Not forgetting that the ion has an overall charge of -2, i.e. there is an additional lone pair of electron on Sb. Thus, [SbF5]2- having 5 bond pairs and 1 lone pair has a square pyramidal shape.

[10:19 pm] chicky

Just completed marking JC1 H2 Test 1.

For 07S19, majority of them did pretty well. Not really because they were good but rather the test was easy. Never in the history did we set such an easy paper on Atoms, Molecules and Stoichiometry and Redox. For the calculations, it was very guided. As part of the effort to stretch students with higher ability, we had included bonus mark question (modified from S Paper), but not many students attempted it. 07S19 has potential to do well. But many of them are complacent and not putting enuff effort. I really hope tat the weaker students will catch up with the better ones soon.

For 07S12, the performance was really bad. Only 4 passes. I can understand that many of them do not have strong foundation in Chemistry. That is why I arranged for an extra lesson on Saturday to give them extra coaching on mole calculations and redox. But it turned out to be a total waste of time. Mainly because the students did not even prepare for the lesson. Throughout that two hours, they were just copying the answers. They failed to realise that they would not understand a single thing unless they processed it through thinking and working.

I am really worried about the coming SPA for 07S12. But I doubt they are. It is my first time having to "beg" students to submit their practical file for marking. I dunno why m I doing this for students who cannot be bothered.

I always believe that practical can help reinforce wat students learn in theory. With the good intent, I planned for practicals on Chemical Energetics for my JC2 H1 students. Once again, it turned out to be a plain waste of time and effort because my students were not at all interested. They questioned me why they were doing experiments. They questioned me why they needed to plot a graph (not as if they will be tested in A lvl Exam). They asked me "can don't do anot". The only consolation I got was that the Arts H1 students (under Mr Tong) were very engaged during the practical and they looked forward to it.

I am trying very hard to improve on the standards of our students but wat I get is disappointment. Maybe I m not suited for this place. It is time to look for other alternatives. The push factor is just too great. Getting more sick and tired.....

[8:26 pm] chicky