9701 · 29.1
Formulas, functional groups and the naming of organic compounds — FAQ
Frequently asked questions for 9701 Formulas, functional groups and the naming of organic compounds. Direct answers first, then deeper explanation — then practise with marking.
What is the difference between a structural formula and a displayed formula?
A displayed formula shows every atom and every bond individually. A structural formula is a condensed version that shows how atoms are grouped, for example, CH₃CH₂OH, which is less cluttered than drawing out all the C-H and O-H bonds.
If a molecule has multiple functional groups, how do I decide which one gets the suffix in the name?
There is a priority order for functional groups in IUPAC nomenclature. For A-Level, the general trend is: Carboxylic acids > Esters > Aldehydes > Ketones > Alcohols > Amines > Alkenes/Alkynes. The highest priority group determines the suffix, and all others are named as prefixes (e.g., 'hydroxy-' for an –OH group if a –COOH is present).
Why is skeletal formula so commonly used in organic chemistry?
Skeletal formulae are quick to draw and easy to read once you are familiar with them. They de-clutter the image, allowing you to focus on the carbon backbone and the functional groups, which are the most important parts for understanding the molecule's shape and reactivity.
What's the difference between butan-1-ol and a primary alcohol?
'Butan-1-ol' is the specific name of a molecule. 'Primary alcohol' is a classification. Butan-1-ol is an example of a primary alcohol because the carbon atom attached to the -OH group is bonded to only one other carbon atom.