Introducing organic chemistry (Edexcel IGCSE Chemistry (Modular): Unit 1): Flashcards
Exam code: 4XCH1
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- FrontOrganic Compounds
Define organic chemistry.
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Define organic chemistry.
Organic chemistry is the study of the structure, properties, and reactions of compounds that contain carbon.
By convention, metal carbonates, carbon dioxide, and carbon monoxide are not classified as organic compounds.
What is a hydrocarbon?
A hydrocarbon is a compound that contains carbon and hydrogen atoms only — no other elements are present.
Define empirical formula.
An empirical formula shows the simplest whole-number ratio of atoms in a compound.
For example, hydrogen peroxide has the molecular formula H2O2 but an empirical formula of HO.
The .......... formula shows the actual number of atoms in a molecule, while the .......... formula shows every atom and bond including their spatial arrangement.
The molecular formula shows the actual number of atoms in a molecule, while the displayed formula shows every atom and bond including their spatial arrangement.
What does a structural formula show, and how does it differ from a displayed formula?
A structural formula shows enough information to make the structure clear but omits most covalent bonds. Only important bonds such as double bonds are shown, and identical groups may be bracketed.
A displayed formula shows every single bond and atom in full spatial arrangement.
True or False?
Isomers have the same molecular formula but different displayed formulae.
True.
Isomers share the same molecular formula but differ in the way their atoms are arranged, giving different displayed formulae and potentially different properties.
Define homologous series.
A homologous series is a family of organic compounds that share the same functional group, the same general formula, similar chemical properties, and a gradation in physical properties.
Each successive member differs by CH2.
Complete the table of formula types.
Formula type
What it shows
Empirical
Molecular
General
Displayed
Formula type
What it shows
Empirical
Simplest whole-number ratio of atoms
Molecular
Actual number of each type of atom
General
Ratio of atoms for a whole family, using n
Displayed
Every atom and bond in spatial arrangement
What is a functional group in organic chemistry?
A functional group is a group of atoms bonded in a specific arrangement that determines the chemical properties of the compound and the homologous series it belongs to.
What do the two parts of an organic compound's name tell you?
The name of an organic compound has two parts: the prefix (or stem) tells you how many carbon atoms are in the longest continuous chain, and the suffix tells you which functional group is present.
What does the prefix meth- indicate?
The prefix meth- indicates that the compound has 1 carbon atom in its longest continuous chain.
In an organic compound's name, the suffix .......... indicates an alkene (a C=C double bond), while the suffix .......... indicates an alcohol (an R-OH group).
In an organic compound's name, the suffix -ene indicates an alkene (a C=C double bond), while the suffix -anol indicates an alcohol (an R-OH group).
How are carbon atoms numbered when naming a compound where a functional group can be on different positions?
When a functional group can occupy different positions, each carbon in the chain is given a number, and this number is included in the compound's name to specify exactly which carbon carries the functional group.
True or False?
The suffix "-anoic acid" indicates the presence of a carboxylic acid functional group.
True.
The suffix -anoic acid is used for carboxylic acids, which contain the functional group R-C(=O)-OH.
What does the prefix di- mean in an organic compound's name?
The prefix di- means that two of the same functional group are present in the compound.
Complete the table of name prefixes and their carbon counts.
Prefix
Number of carbons
Meth...
Eth...
Prop...
But...
Pent...
Hex...
Prefix
Number of carbons
Meth...
1
Eth...
2
Prop...
3
But...
4
Pent...
5
Hex...
6
What suffix and family name are used for a compound with the functional group R-NH2?
The suffix -amine is used, and the compound belongs to the amine family of organic compounds.
Define substitution reaction.
A substitution reaction is one in which one functional group (or atom) is replaced by another, leaving the carbon skeleton intact.
What happens in an addition reaction, and how many products are formed?
In an addition reaction, two or more molecules combine to form a single, larger molecule with no other products.
For example, bromine adds across the C=C double bond of ethene to form dibromoethane.
True or False?
In complete combustion of a hydrocarbon, carbon dioxide and water are the only products.
True.
Complete combustion occurs when there is excess oxygen. The carbon in the fuel is fully oxidised to carbon dioxide and the hydrogen forms water.
Define addition reaction.
An addition reaction is one in which two molecules combine to form a single, larger molecule, with no other products formed.
When methane reacts with bromine under ultraviolet light, a .......... reaction occurs: one hydrogen atom is replaced by a bromine atom, producing bromomethane and ...........
When methane reacts with bromine under ultraviolet light, a substitution reaction occurs: one hydrogen atom is replaced by a bromine atom, producing bromomethane and hydrogen bromide.
What are the products of complete combustion compared to incomplete combustion of a hydrocarbon?
Complete combustion (excess oxygen) produces carbon dioxide and water only.
Incomplete combustion (limited oxygen) produces carbon monoxide, unburned carbon (soot), and water.
True or False?
An addition reaction always produces exactly one product.
True.
By definition, an addition reaction forms a single product when two molecules combine. If more than one product forms, the reaction is classified differently (e.g. as substitution).
Complete the table summarising the three main types of organic reaction.
Reaction type
What happens
Substitution
Addition
Combustion
Reaction type
What happens
Substitution
One functional group is replaced by another
Addition
Two molecules combine to form one larger molecule with no other products
Combustion
Organic substance reacts with oxygen to form carbon dioxide (or CO) and water
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