4 Introduction to hydrocarbons Flashcards
What are hydrocarbons?
They are molecules that contain only carbon and hydrogen.
How are carbon atoms joined to hydrogen atoms?
By single bonds.
What is the empirical formula?
The simplest whole number ratio of atoms in a compound.
What is the molecular formula?
The actual number of atoms in each element of a compound.
What is a homologous series?
A series of compounds with similar chemical properties because they have the same functional group.
How can the members of a homologous series be represented?
Using a general formula.
What is the general formula?
A formula which can be applied to a whole family of compounds.
What is the displayed formula?
A formula that shows all the bonds in a molecule as individual lines. Each line represents a pair of shared electrons in a covalent bond.
What is the structural formula?
It shows how the atoms in a molecule are joined together.
What is the structural formula for butane?
CH3CH2CH2CH3
How do you find out the empirical formula from the molecular formula?
You take the subscripts from the molecular formula and then reduce them to the simplest whole number ratio.
How do you find out the molecular formula from the empirical formula?
Find the relative formula mass of the compound and then divide or times appropriately.
What is the functional group?
An atom or a group of atoms that determine the chemical properties of a compound.
What is isomerism?
When more than one compound have the same chemical formula but different chemical structures.
What is the general formula for alkenes?
CnH2n
What is the general formula for alkanes?
CnH2n+2
How do you know which end of the chain to number from?
You number from the end which produces the smaller numbers in the name.
What are structural isomers?
They are molecules with the same molecular formula, but different structural formulae
What is a straight chain?
It is an unbranched chain.
What is combustion in terms of reactions of hydrocarbons?
Is when excess oxygen gives rise to carbon dioxide and water, together with the release of a large amount of heat energy.
What does the prefix ‘di’ mean?
It indicates the presence of two identical branches in the molecule.
What is an example of combustion?
Propane burning.
What is the equation of propane burning?
C3H8 + 5O2 –> 3CO2 + 4H2O
What is substitution in terms of reactions of hydrocarbons?
It occurs when an atom or group of atoms is replaced by a different atom or group of atoms.
