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.

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.

Comparing Bond Energy Using Hybridisation

Let's start our discussion with these 2 compounds, methane and ethene.

comparing bond energy using hybridisation methane vs ethene

If we want to compare the C-H bond energy in both compounds, which has a more stable C-H bond?

You notice we cannot use bond energy values from the Data Booklet to figure this out, as there is only 1 C-H bond energy value in the Data Booklet!

So therefore we would need to look at the state of hybridisation of carbon to eventually compare the C-H bonds in both compounds.

Hybridisation

Hybridisation is the mixing of valence orbitals to form sigma bonds.

I have a previous detailed video lesson on hybridisation of carbon so if you are not sure about this concept, do give this video a look!

comparing bond energy using hybridisation hybridisation s character and orbital length

The table above summarises the different states of hybridisation of carbon, the percentage s character of the hybridised orbitals, and the length of orbitals.

- sp³ hybridised orbital has 25% s character and is longer and further away from the nucleus
- sp hybridised orbital has 50% s character and is shorter and closer to the nucleus

The reason why a hybridised orbital with greater s character is shorter is because s orbital is more stable and closer to the nucleus than p orbital.

comparing bond energy using hybridisation s orbital vs p orbital

1. Compare C-H Bond

So back to our example of methane and ethene, we can first determine the state of hybridisation of the carbons first.

comparing bond energy using hybridisation compare C H bond in methane and ethene

Carbon in methane is sp³ hybridised, so its orbitals are longer. The C-H bond in methane will be weaker and has lower bond energy.

Carbon in ethene is sp² hybridised, so its orbitals are shorter. The C-H bond in ethene will be stronger and has higher bond energy.

2. Compare C-C bond

Let's have another example to compare C-C bonds.

comparing bond energy using hybridisation compare CC bond example

If we want to compare C-C double bond between C_x-C_y and C_y-C_z, we would again need to consider their state of hybridisation.

C_x is sp² hybridised and the sp² orbital is slightly longer while C_y and C_z are sp hybridised and the sp orbitals are slightly shorter.

Therefore C_x-C_y will have a longer and weaker bond with lower bond energy, and C_y-C_z will have a shorter and stronger bond with higher bond energy.

comparing bond energy using hybridisation compare CC bond using hybridisation