is the simplest whole number ratio of the number of atoms if each element in a compound.
E.g: All alkenes with one double bond has the empirical formula CH2
Define molecular formula?
Molecular formula gives the actual number of atoms of each element present in a molecule.
Define general formula?
General formula is the simplest algebraic formula to represent any member of a homologous series.
E.g: any alkane with n carbons has the formula CnH2n+2
Define a Structural formula?
A structural formula gives minimal detail to show how the atoms are arranged in the molecule.
E.g: Butanol C4H10O can exist in four different forms (structural isomers) all with the same molecular formula but with different arrangement of the atoms ..
CH3CH2CH2CH2OH = Butan-1-ol
(CH3)2CHCH2OH = 2-methylpropan-1-ol
(CH3)3COH = 2-methylpropan-2-ol
Define a displayed formula?
Gives the most accurate representation of the molecule, showing all the atoms and bond present, and can give indication of the relative positions of the atoms in space.
Define a skeletal formula?
Is a simplified organic formula with carbon atoms shown as a skeleton and all the hydrogen atoms of the alkyl chains removed except for those of functional groups.
explain what structural isomerism means?
In structural isomerism the structural arrangements of atoms are different, the carbon chain may be different, or the functional group and / or its position in the molecule may be different. Structural isomers of a compound have the same molecular formulae, but have different structural and displayed formula.
Define stereo isomerism?
The structural formulae are identical but the displayed formulae are different because the isomers have different arrangements of the atoms in space. There are two types, E/Z isomers.
cis and trans stereo isomers
Describe the method of naming alkanes?
-Identify the longest carbon chain.
-Number the carbons to which the alkyl substituent group is attached.
-Put the two parts together and name the whole compound.
Define Functional groups? and give examples?
A functional group is a group of atoms found in a compound that are responsible for the characteristic reactions of the compound.
How to name halogenoalkanes?
-Find the longest carbon chain.
-Put the position(loest number possible) and name of the halogen in front.
The halogen is always halo- (e.g: bromo, iodo)
-Find the longest Carbon chain and change the ending from -ane to -ene.
-Find the lowest possible number for the c=c bond position is indicated by the number in the name(unless if there is only one possibility.)
E.g : Pent-2-ene
- Find the longest carbon chain and name the alkane(without the -e)
- then the lowest position of the -OH group is indicated by the number followed by -ol.
Are organic compound that contain carbon and hydrogen only.
Define saturated hydrocarbons?
Is a hydrocarbon with single bonds only.
Define unsaturated hydrocarbons?
Is a hydrocarbon containing carbon-carbon multiple bonds.
Define the term an Aliphatic hydrocarbon
Is a hydrocarbon with carbon atoms joined together in straight or branched chain.
Define an alicyclic hydrocarbon?
Is a hydrocarbon with carbon atoms joined together in a ring structure.
Define the term homologous series?
is a series of organic compounds with the same functional group but with each successive member differing by CH2. ( they also have similar chemical properties)
alkanes are saturated straight chained hydrocarbons with single c-c bonds only. For alkanes each carbon atom is bonded to four other atoms. Each carbon has a tetrahedral shape with a bond angle of 109.5*
In a homologous series what reacts?
it is the functional group that reacts in a homologous series.
is a system of naming compounds.
Define what is meant by an alkyl group?
An alkyl group is an alkane with a hydrogen atom removed.
(An alkyl group is often shown as 'R' )
Naming compounds with functional groups?
-Identify the parent chain ( laargest unbranched chain of carbon atoms)
-Name the stem of the parent chain. e.g~ Meth- Eth-
-Identify any alkyl chains or functional groups. -Alkyl groups are placed before the stem name.
-Identify the name of the prefix or suffix for the functional group. prefix is added before the stem and a suffix is added after the stem.
-Number any alkyl groups and functional groups to show their position on the parent chain.