Formulas, Functional Groups & the Naming of Organic Compounds (Cambridge (CIE) A Level Chemistry): Flashcards
Exam code: 9701
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Define hydrocarbon.
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Cards in this collection (36)
Define hydrocarbon.
A hydrocarbon is a compound made up of carbon and hydrogen atoms only.
Why is carbon able to form such a vast number of compounds?
Carbon can form strong covalent bonds with itself, allowing it to form long chains, branched chains and rings — giving rise to an almost infinite variety of compounds.
True or False?
Ethanol is a hydrocarbon.
False.
Ethanol contains an oxygen atom as well as carbon and hydrogen. Hydrocarbons must contain carbon and hydrogen atoms only.
Define homologous series.
A homologous series is a group of organic compounds that share the same functional group, with each successive member differing by CH2.
Each successive member of a homologous series differs by ........... Every time a carbon is added to the chain, .......... hydrogen atoms are also added.
Each successive member of a homologous series differs by CH2. Every time a carbon is added to the chain, two hydrogen atoms are also added.
Define alkane.
Alkanes are the simplest hydrocarbons, containing only carbon and hydrogen atoms joined by single covalent bonds with no functional group.
What is the general formula of the alkane homologous series?
The general formula is CnH2n+2, where n is the number of carbon atoms.
True or False?
Alkanes can be linear, branched or cyclic in structure.
True.
Alkanes can exist as linear, branched or cyclic structures, all containing only C–C and C–H single bonds.
Methane has .......... carbon atom(s) and the formula .........., while pentane has .......... carbon atoms and is a liquid at room temperature.
Methane has one carbon atom and the formula CH4, while pentane has five carbon atoms and is a liquid at room temperature.
Define functional group.
A functional group is a specific atom or group of atoms in an organic molecule that determines its physical and chemical properties.
What does the letter R represent in organic structural formulae?
R represents any other atom or group of atoms in the molecule, except hydrogen.
True or False?
All members of a homologous series share the same functional group and general formula.
True.
A homologous series is a group of organic compounds sharing the same functional group, the same general formula and the same chemical properties.
Define general formula.
A general formula is an algebraic formula using letters and numbers that represents an entire homologous series of compounds.
The .......... formula shows how atoms are bonded to each carbon atom, while the .......... formula is a 2D representation showing all atoms and all bonds.
The structural formula shows how atoms are bonded to each carbon atom, while the displayed formula is a 2D representation showing all atoms and all bonds.
What is the skeletal formula and how does it differ from the displayed formula?
The skeletal formula is a simplified displayed formula in which all C–H bonds and carbon symbols are removed, leaving only the carbon skeleton and functional groups.
True or False?
The displayed formula of a molecule shows only the carbon skeleton with functional groups highlighted.
False.
The displayed formula shows all atoms by their symbols and all bonds. It is the skeletal formula that removes C–H bonds and carbon symbols.
Organic molecules are classified by their dominant ........... Compounds with the same functional group but differing by .......... per member form a .......... series.
Organic molecules are classified by their dominant functional group. Compounds with the same functional group but differing by CH2 per member form a homologous series.
Give the general formula for alkanes and explain what n represents.
The general formula of alkanes is CnH2n+2, where n is the number of carbon atoms in the molecule.
Define stem (organic nomenclature).
A stem is the part of an organic compound's name that indicates the number of carbon atoms in the longest chain of the molecule (e.g. meth- = 1, eth- = 2, prop- = 3).
When numbering the carbon chain to name an organic compound, which end do you start from?
Number from the end that gives the lowest possible locant numbers to the substituents or functional groups.
True or False?
Side chains are named by changing the -ane ending of the parent alkane to -yl.
True.
For example, a methane-derived side chain becomes a methyl group and an ethane-derived side chain becomes an ethyl group.
When two identical side chains are present, the prefix .......... is used. When three identical side chains are present, the prefix .......... is used.
When two identical side chains are present, the prefix di- is used. When three identical side chains are present, the prefix tri- is used.
What IUPAC suffix is used for ketones, and what suffix is used for carboxylic acids?
Ketones take the suffix -one (e.g. propanone) and carboxylic acids take the suffix -oic acid (e.g. ethanoic acid).
Define aliphatic compound.
An aliphatic compound is an organic compound with a straight or branched carbon chain, including cyclic compounds that do not contain a benzene ring.
True or False?
When naming a compound with two different alkyl side chains, the side chains are listed in order of increasing chain length.
False.
When different alkyl side chains are present, they are listed in alphabetical order, not by chain length.
In systematic nomenclature, numbers are separated from words by a .......... and adjacent numbers are separated from each other by a .......... .
In systematic nomenclature, numbers are separated from words by a hyphen and adjacent numbers are separated from each other by a comma.
What are the IUPAC prefixes used for fluorine, chlorine, bromine and iodine substituents in halogenoalkanes?
The prefixes are fluoro-, chloro-, bromo- and iodo- respectively, placed before the parent chain name with the locant number.
Define molecular formula.
A molecular formula shows the actual number and type of each atom present in one molecule of a compound.
Define empirical formula.
An empirical formula shows the simplest whole number ratio of the elements present in one molecule of a compound.
What is the molecular formula of ethanoic acid and what does it tell you?
The molecular formula of ethanoic acid is C2H4O2, showing that one molecule contains 2 carbon, 4 hydrogen and 2 oxygen atoms.
True or False?
The empirical formula and molecular formula of a compound are always the same.
False.
The empirical formula gives the simplest ratio of atoms, while the molecular formula gives the actual number. For example, ethanoic acid has molecular formula C2H4O2 but empirical formula CH2O.
The .......... formula shows the actual number of atoms in a molecule, while the .......... formula shows the simplest whole number ratio of those atoms.
The molecular formula shows the actual number of atoms in a molecule, while the empirical formula shows the simplest whole number ratio of those atoms.
How do you convert a molecular formula into an empirical formula?
Divide the number of each type of atom by their highest common factor to give the simplest whole number ratio.
True or False?
Ethanol (C2H6O) and ethanoic acid (C2H4O2) have the same empirical formula.
False.
Ethanol (C2H6O) has empirical formula CH3O, while ethanoic acid (C2H4O2) has empirical formula CH2O. They are different.
To find the empirical formula from percentage composition, first convert the percentages to .......... of atoms by dividing by the .......... of each element.
To find the empirical formula from percentage composition, first convert the percentages to moles of atoms by dividing by the relative atomic mass of each element.
Glucose has the molecular formula C6H12O6. What is its empirical formula?
The empirical formula of glucose is CH2O, obtained by dividing all subscripts by the highest common factor of 6.
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