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AQA A Level Chemistry復習筆記3.1.2 Types of Formulae

Category: A-level課程, 教材筆記, 福利干貨 Date: 2022年6月30日下午3:15

Types of Formulae

The?general formula?is a formula that represents a?homologous series?of compounds using letters and numbers
- Eg. the general formula of alkanes is CnH2n+2
- A homologous series is a group of organic compounds that have the same functional group, the same general formula and the same chemical properties
The?structural formula?is a formula that shows how the atoms are bonded to each carbon atom in a molecule
The?displayed formula?is a 2D representation of an organic molecule showing?all?its atoms (by their?symbols) and their bonds (by single, double or triple bonds)
The?skeletal formula?is a simplified displayed formula with all the carbon and hydrogen (C-H) bonds removed

Overview of the Formulae of Organic Compounds Table

3.1-An-Introduction-to-AS-Level-Organic-Chemistry-Formulae-of-Organic-Compounds_1

Worked Example

Drawing skeletal formulae of molecules

Draw the skeletal formula of the following molecules:

CH3(CH2)3OH
(CH3)2CHCH2OH
CH3CH2OCH2CH3

Answer:

3.1-An-Introduction-to-AS-Level-Organic-Chemistry-Answer-Worked-example-Drawing-skeletal-formulae-of-molecules

Worked Example

Drawing displayed formulae of molecules

Draw the displayed formula of the following molecules: Copy-of-WE-An-Introduction-to-AS-Level-Organic-Chemistry-Drawing-displayed-formulae-of-molecules_1

Answer

3.1-An-Introduction-to-AS-Level-Organic-Chemistry-Answer-Worked-example-Drawing-displayed-formulae-of-molecules_1

Molecular & Empirical Formulae

The?molecular formula?shows the number and type of each atom in a molecule
- Eg. the molecular formula of ethanoic acid is C2H4O2
The?empirical formula?shows the simplest whole number ratio of the elements present in one molecule of the compound
- Eg. the empirical formula of ethanoic acid is CH2O

Worked Example

Deducing molecular & empirical formulaeDeduce the molecular and empirical formula of the following compounds: Copy-of-WE-Deducing-molecular-empirical-formulae_1