Organic Chemistry

O-Level Chemistry: An Introduction to Organic Chemistry

Organic Chemistry is the study of organic compounds.

Organic compounds are compounds which contain the element carbon. Most organic compounds also contain hydrogen. Organic compounds which contain carbon and hydrogen only are known as hydrocarbons.

Organic compounds may also contain other elements such as chlorine, nitrogen, oxygen, etc.

Do note that there are some exceptions. Carbon monoxide (CO), carbon dioxide (CO₂), calcium carbonate (CaCO₃), etc are not classified as organic compounds even though they contain carbon.

In this post, we will look at the following basic fundamentals when it comes to organic chemistry:

Homologous Series
Functional Group
Naming of Organic Compounds
Formulae

A) Homologous Series

A homologous series refers to a family of organic compounds with the same general formula and similar chemical properties.

Do note that some textbooks defined homologous series as a family of organic compounds with the same functional group and similar chemical properties. This sounds a bit off considering that alkanes homologous series does not contain any functional group.

The homologous series covered in GCE O-Level Pure Chemistry syllabus (and other Sec 4 IP Chemistry syllabus) in Singapore are: Alkanes, Alkenes, Alcohols and Carboxylic Acids.

Organic compounds in the same homologous series have the following characteristics:

Represented by a General Formula
Regularly increasing relative molecular masses from one member to the next member
Can be prepared by similar methods
Gradual change in physical properties from one member to the next member
Similar chemical properties
Same functional group (except alkanes homologous series)

B) Functional Group

A functional group is defined as an atom or a group of atoms that gives a molecule its characteristic properties.

All molecules containing the same functional group will behave similarly towards the same chemical reagents, i.e. they have the same chemical properties.

Following are some homologous series and their functional groups that are covered in the Pure Chemistry syllabus:

Alkanes – Do not have any functional groups. There are only C-C and C-H covalent bonds in the molecule.
Alkenes – Contain the carbon-carbon double bond, C=C.
Alcohols – Contain the hydroxyl group, -OH.
Carboxylic acids – Contain the carboxyl group, -COOH.

C) Naming of Organic Compounds

The naming of organic compound is divided into three parts:

Part 1: Length of the parent chain i.e. the number of carbon atoms in the longest continuous (unbroken) chain [also known as the Prefix]

Prefix	meth-	eth-	prop-	but-
Number of carbon atoms in molecule	1	2	3	4

Part 2: Functional Group found in main parent chain [also known as the Suffix]

Homologous series	alkane	alkene	alcohol	carboxylic acid
Suffix	-ane	-ene	-ol	-oic

Part 3: Side group that are attached to the main parent chain [also known as Substituent]

Substituent	-Cl	-Br	-I	-CH₃
Name of side group	chloro	bromo	iodo	methyl

For example, ethene is an alkene with two carbon atoms per molecule.

Ethene - Full Structural Formula — Full Structural Formula of Ethene

For example, propanol is an alcohol with three carbon atoms per molecule.

Propanol - Full Structural Formula — Full Structural Formula of
Propanol

D) Formulae

They are four types of formulae that we can use to represent a particular organic compound. This also means that you will be tested in Chemistry examinations on all four types of formulae which are:

Empirical formula which is the simplest whole no. ratio of atoms of each element
Molecular formula which is the total no. of atoms of each element in each molecule
Structural formula which shows how atoms are arranged in the molecule
Full Structural formula which shows all the bonds between atoms in a molecule

I hope you find the content easy for your understanding and if you have any questions, leave me a comment below. Feel free to share this blog post with your friends.

Do stay tuned to the upcoming posts as we will be looking at more key concepts in Organic Chemistry as well as some GCE O-Level Pure Chemistry and Sec 4 IP Chemistry examination questions.

Subscribe to my blog to receive 2 updates per month sent to your email!

PS: Under related articles below, there are several blog post discussions and questions related to Organic Chemistry. You can also do a keyword search using the search box at the top right hand corner.

PPS: If you need help with your O-Level Pure Chemistry and IP Chemistry, do join us in our weekly O-Level Pure Chemistry & IP Chemistry Tuition Class. Consistency is key to master Chemistry.

Tan Hui Yu Chung Cheng High School Main A1 for O-Level Pure Chemistry

O Levels Organic Chemistry: Common Conceptual Mistakes by Students

During the Organic Chemistry Mastery Workshop 2009 in July, we noticed several misconceptions by students that surfaced again for this current batch of GCE O Levels students, just like the previous years’ batches.

Just a quick note on 2 common errors (mentioned in Up Your Chemistry Grades Now) that you would need to be aware of, so that you can avoid them at all cost.

Hope you will find this information useful to you.

PS: Do leave me a comment. I would love to hear from you.

O Levels Chemistry 2008 Exam Question: Organic Chemistry in Paper 1 (MCQs) – Part 2

In the previous blgopost we have discussed on 3 MCQ questions on Organic Chemistry that came out in 2008 GCE O Levels Chemistry Exams. Let’s continue with the rest of the MCQ questions that are related to Organic Chemistry.

Question 1: under sub-topic “Carboxylic Acids”
The reaction between a carboxylic acid, CxHyCO2H, and an alcohol, CnH2n+1OH, produces an ester.
How many hydrogen atoms does one molecule of the ester contain?
A.? y + 2n
B.? y + 2n + 1
C.? y + 2n + 2
D.? y + 2n + 3
PS: Tricky question that ALL Pure Chemistry students must know how to answer

Question 2: under sub-topic “Carboxylic Acids” [Read more…] about O Levels Chemistry 2008 Exam Question: Organic Chemistry in Paper 1 (MCQs) – Part 2

O Levels Chemistry 2008 Exam Question: Organic Chemistry in Paper 1 (MCQs) – Part 1

Hi Students (and parents),

Thank you for all your email enquries on our annual Organic Chemistry Mastery Workshops 2009 for O Level students.

As mentioned that in 2008 GCE O Levels Chemistry Exams, Organic Chemistry plays a large part of the questions that came out in Paper 1 (Multiple Choice Questions) and 2 (Written).

Today i am going to share with you some of the multiple choice questions that came out. I will help you by directing you to the “sub-topics” of Organic Chemistry that the question is based on:

Question 1: Under sub-topic ” Fuels”
In how many of the following can paraffin (kerosene) be used as the energy source?
Aircraft, Air Conditioning Units, Cars, Domestic Cooking, Heavy Lorries, Power Stations
A) 1
B) 2
C) 3
D) 4

Question 2: under sub-topic “Alkanes”
Which statements are true of alkanes?
1. Their general formulae is CnH2n [Read more…] about O Levels Chemistry 2008 Exam Question: Organic Chemistry in Paper 1 (MCQs) – Part 1

Secrets: Why you need to master Organic Chemistry in GCE O Levels?

Hi students,

As mentioned in my previous blogpost, Organic Chemistry is of extreme importance in GCE ‘O’ Levels Chemistry Exams, due to 2 main reasons (based on my analysis of Past Years Exam Papers):

High weightage about 18 – 25 marks (15 – 21%) of your written O Level Chemistry Exams
In Year 2008 O Level Chem Exams, the last Question (Either/Or Question worth 10marks) in Paper 2 are both Organic Chemistry. This means there is no way you can escape Organic Chemistry

Need MORE reasons (that i observed last 3-4 years) why you need to MASTER Organic Chemistry????

1) Organic Chemistry is an independent component that you can master on its own, regardless of how you have fared for other previous chapters

2) Organic Chemistry is in fact VERY EASY – all the 5 chapters/topics in Organic Chemistry are inter-linked and once you master 1 topic, you will be able to master the other topics, with ease once you have the correct methodology

3) Contrary to many students believed that Organic Chemistry needs lots of memorisation, Organic Chemistry DOES NOT need lots of memory work. You just need to associate it to our everyday life and be clear of how each topics are interlinked with each other – and you will score well for it!

4) Majority ALL schools in Singapore (Both GCE O Levels and IGCSE/IB) rushed through Organic Chemistry chapters in June / July in order to finish the syllabus and welcome the School Prelims Exams. Many of the teachers only glanced through it with their students (“surface learning”) in order to finish the syllabus. There are even 1-2 schools (my students are in these schools) that actually asked them to READ ON THEIR OWN!!!! Gosh! You can’t learn Organic Chemistry just by reading textbook? cos concepts are required.

If you are of these students that aim to do well for your GCE ‘O’ Levels Chemistry Exams, i urge you to master Organic Chemistry. Spend time mastering it, please.

If you are facing the following problems in mastering Organic Chemistry, do check out the Early Bird Registration (by 15th July 2009) for our annual O Levels Organic Chemistry Mastery Workshop 2009

I will see you at the workshop! =)

Sean

>> Click HERE to find out more about Organic Chemistry Mastery Workshops [Read more…] about Secrets: Why you need to master Organic Chemistry in GCE O Levels?