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
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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


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