What are the different types of JC Chemistry tuition classes available at your centre?

We have 3 modes of learning for students to choose from: weekly physical classes at Bishan; weekly online lessons via Zoom; and on-demand video lessons.

Are you the only Chemistry tutor conducting the classes or do you engage other tutors to do that?

Please be rest assured that I conduct all my classes personally and I do not engage other tutors to teach at my centre.

How well do your students perform after attending your H2 Chemistry tuition classes?

Most of my students showed improvements by at least 3 grades and more than 80% have attained distinction for A Levels. The earlier the students join my classes, the more confident I am in improving their grades.

What is your class size at Bishan?

Usually the class size is around 10 to 12 students. Max class size is 16 pax.

Is there makeup lesson if I miss a class?

Yes makeup lesson is available in the same week subject to availability. If makeup class is not possible, the student can view the recorded video lessons at Google Classroom.

Do you have trial lesson available? How much is it?

Yes we do. Fees for trial lesson are for Bishan class and for Zoom online class.

Does your centre offer O Level chemistry tuition? Do you teach IB / IP chemistry tuition? How about H1 Chemistry?

Chemistry Guru specialises in H2 Chemistry for JC1 and JC2 or IP Year 5 and IP Year 6 students only. Find out all the information about A Level H2 Chemistry and the detailed comparison between H1 and H2 Chemistry. We do not conduct lessons for H1 Chemistry, O Level Chemistry, IB Chemistry or IP Chemistry at IP Year 3 and IP Year 4.

Drawing Dot and Cross Diagrams

In this video created by Chemistry Guru, Singapore's leading JC Chemistry tuition centre, we want to learn how to draw dot and cross diagrams for molecules and ions in Chemical Bonding.

Drawing dot-cross diagram is a fundamental and essential technique for us to determine the lewis structure and shape of molecules and polyvalent ions.

For A Level Chemistry Syllabus we now have elements that can expand octet, and species that can form dative bonds.

So we have to systematically deduce the arrangement of electrons instead of doing it by trial and error.

Guidelines for Drawing Dot Cross Diagram

There are a few guidelines that are useful:

1. The atom that needs the most electrons to be stable is the central atom.

2. For anions, electrons are added to the more electronegative atom. For cations, electrons are removed from the less electronegative atom.

3. The central atom will distribute its electrons to the surround atoms to make them stable or octet.

4. An atom will form the same number of bonds as the number of additional electrons required for stablility. For instance carbon needs 4 electrons to be octet so will form 4 bonds.

5. The central atom will expand octet to form more bonds if necessary. Remember more bonds means more energy is released so the species will be more stable.

6. Only Period 2 elements cannot expand octet, ie only these 4 elements carbon, nitrogen, oxygen and fluorine cannot expand octet. This means that octet rule is the exception and expansion of octet is the norm.

dot cross diagram guidelines