Naming Organic Molecules Part 2: different types of formulae

What have we done so far?

In the first of three posts about naming and drawing structures for organic molecules we classified hydrocarbons as either saturated or unsaturated. We learned how to systematically name alkanes, a family of hydrocarbons with single covalent bonds only,

Salbutamol otherwise known as ventolin for asthma treatment. Ventolin inhalers

Salbutamol otherwise known as ventolin for asthma treatment. Ventolin inhalers

Formulae in organic chemistry, how much information?

There are three main types of chemical formula in organic chemistry each providing different information. The formula used will depend on the circumstances

  • Molecular Formula: The molecular formula shows the numbers and types of atoms in the molecule
  • Full Structural Formula: A full structural formula shows all the covalent bonds in the molecule.
  • Condensed structural formula: A condensed structural formula shows carbon atoms with the total number of atoms bonded with them. 

Salbutamol. the molecule on the right represents yet another type of formula you will come across regularly. Which of the three formula types listed is it most closely related to and why?  It can save a lot of space if you miss out all the carbon atoms and just show the covalent bonds in the skeleton. The carbon atoms sit in the corners. If only three covalent bonds come to a point then you know that there is a hydrogen atom attached at that point as qwell.

Look at the structure carefully and work out the molecular formula for salbutamol.  Check your answer by going to chemspider and plug salbutamol into the search tool. This is a useful site if you find the name of an ingredient on a product and want to find out more about it. For instance triclosan is a molecule receiving a lot of attention at the moment. Check it out on chemspider and find out why it is a rather controversial molecule.

Finally you need to be competent moving from a full structural formula to a condensed structural formula and vice versa. Make sure that you have got the hang of this by watching the short 4 minute video

 For Educators

You can trial the full powerpoint here. The resource is fully animated and scaffolded. It can be used in the classroom for teacher led instruction. It could  be used as a student self learning programme in a computer room or for homework.

You can purchase the powerpoint and associated assessment exercises on my online store at teachers pay teachers
Ninth, Tenth, Eleventh, Twelfth -

hydrocarbons: Systematically naming organic molecules

Organic Chemistry

comet landingOrganic chemistry is undoubtedly the most important branch of chemistry. At the molecular level it can be the study of life itself. A washing machine sized robot named Philae has just started an eternal piggy back ride on a lump of rock dating back to the beginning of time. Its mission to discover if life starting molecules are part of the frozen package. A billion dollar launch and ten years later a permanent stop off on an asteriod where it will drill below the surface sniffing out organic compounds before drifting through the cosmos till the end of time. Organic chemistry started the moment supernovae starting spewing carbon atoms into the universe. Its an important subject Ok got a bit carried away. Organic chemistry is the study of carbon and its compounds with hydrogen  and a few other elements mainly oxygen nitrogen phosphorus and sulphur

Hydrocarbons the simplest  organic molecules

2,2,4-trimethylpentaneThis is a simple molecule but even governments of small countries are prepared to go war to secure supplies of this hydrocarbon. Its a hydrocarbon because it contains the elements carbon and hydrogen only. The  research octane number or RON of  gasoline is a measure of its efficiencey compared with 2,2,4-trimethyl pentane under test conditions. The number is displayed at the pump. Just to confuse you this molecule also goes by the name isooctane.

Chemical structure and systematic naming of organic molecules

How do we write structural formulae for organic molecules and give them a unique name that everyone understands (Chemists call this a systematic name). I have tried to explain this in the video starting with the simplest organic molecules, the hydrocarbons. Back to the cosmos again The fuel that carried Rosetta away from earth on a trajectory that would see it 10 years later bounce along the surface of a comet was a hydrocarbon, hydroxyl terminated polybutadiene (HTBD). On this planet the vast majority of polybutadiene is used in tyre manufacture for vehicles driving on high octane fuel

Finished the  book, watch the movie

Stop the video when prompted and attempt the questions towards the end to check understanding.

 For Educators


You can purchase the powerpoint and associated assessment exercises on my online store at teachers pay teachers
Ninth, Tenth, Eleventh, Twelfth -

Trial the powerpoint first


Adrenaline Amphetamines: Introduction to functional groups in organic chemistry

Adrenaline Amphetamines: Introduction to functional groups in organic chemistry

Adrenaline Amphetamines: Introduction to functional groups in organic chemistry


Functional groups

some functional goups edublogs

Functional groups are specific groups of atoms or bonds within molecules that are responsible for their properties.The same functional group will do similar chemistry regardless of the size of the molecule it is a part of. The alcohol group in a molecule improves its solubility in water. Molecules with an amine group can smell of rotting fish. Many neurotransmitters are amines.


Amphetamine mimics the properties of adrenaline as a consequence of similarities between the chemical structures of the molecules

Adrenaline kick starts the body when a fast reaction is needed. It is released in response to anxiety or fear. This is the basis of the so called fight or flight reaction. molecules.


During the second world war amphetamines including methamphetamine were used by opposing sides for their stimulant and performance enhancing effects. As authorities became aware of the addictive properties of the drug restrictions were put in place to limit 

Organic chemists are molecular architects and they love to design new structures often with predictable properties. Molecules are held together by strong covalent bonds . Chemists understand how to detach single or complete groups of atoms and screw a completely different structure into place. They can even weld two different molecules together.

Methamphetamine pseudoephridine and phenyl 2 propanone.

adrenaline amphetamine methamphetamine

The TV series Breaking Bad gets most of the chemistry right in its portrayal of high school chemistry teacher Walter White as he “cooks’ methamphetamine from two different starting materials. Red phosporus is used in the mix when you start with pseudoephidrine. An unfortunate side reaction with moisture to produce toxic phosphine gas was used to spectacularly dispatch two drug dealers in his mobile lab. The p2p route which he eventually adopts has its problems starting with phenyl 2 propanone. Many organic molecules behave like a pair of gloves, they have a left handed  and right handed version both with four fingers and a thumb, identical mirror images of each other. The identical mirror image molecules are known as enantiomers

Chemistry is at the core of another violent scene (S.4E.1). Walt implies his product is enantiomerically pure in “Box cutter” . He asks Victor, “If our reduction is not stereospecific, then how can our product be enantiomerically pure?” Since he’s not a chemist, Victor was unable to answer, and Gus slits his throat with a box cutter while he is thinking about it.

Complex organic structures, where do the names come from?

Year 13 Chemistry exam revision, AS90698 L3 organic 2011

Tackle the 2011 organic paper then check with assessment schedule . Make sure that you see me about any problems with the paper. Make an appointment for extra help if required.  

2011 90698 organic paper 90698-exm-2011

2011 90698 organic paper assessment schedule 90698-ass-2011

Youtube videos to help with revision

optical isomers

naming organic molecules revision

functional groups in organic chemistry

optical and geometric isomers



good luck







Organic Chemistry Tutorial: Structural geometrical and optical isomerism

Many Biological molecules are optically active. Optically active organic molecules rotate plane polarised light. To be optically active they must have at least one asymetric carbon in their structure. Most optically active biological molecules rotate light to the left. Optical isomers are called enantiomers and they are non superimposable mirror images of each other. Enantiomers are identical, the only difference between them being the direction in which they rotate light. Special proceedures are used to separate them.

In nature only one enantiomer is biological active.

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