Basic Concepts and Hydrocarbons Flashcards
What is a functional group?
A group of atoms responsible for the characteristic reactions of a molecule
What does nomenclature mean?
Naming organic compounds
How many bonds to carbon form?
4
What is the functional groups of alcohols?
-OH
What is the functional group of carboxylic acids?
-COOH
What is the functional group of alkenes?
-C=C-
How many bonds do oxygen form?
2
What is the general formula?
An algebraic formula that can describe any member of a family of compounds
What is the general formula of alcohols?
CnH2n+1OH
What is a homologous series?
A family of compounds that have the same functional group and general formula
What do consecutive members of a homologous series differ by?
-CH2-
What is the general formula for alkanes?
CnH2n+2
What is the molecular formula?
Gives the actual number of atoms of each element in a molecule
What is the empirical formula?
Gives the simplest whole number ratio between atoms of each element in a compound
How do you find the empirical formula if given the molecular formula?
Divide the molecular formula by the smallest number of atoms for a given element in a molecule
What is the functional group of an ester?
-COO
What is the structural formula?
Shows the atoms carbon by carbon, with the attached hydrogen and functional groups
E.G. Ethane = CH3CH3
What is a displayed formula?
It shows how all the atoms are arranged, and all the bonds between them
What does the skeletal formula show?
Just the carbons, joined in a zig-zag to show where each bond ends
What is an aromatic compound?
An organic compound that contains a benzene ring
What are the 2 ways of drawing a benzene ring?
⏣ or ⌬
What is an aliphatic compound?
Compounds that contain carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings
What is an alicyclic compound?
An organic compound that contains carbon and hydrogen joined together in a non-aromatic ring (doesn’t contain a benzene ring)
What is an alkyl group?
A hydrocarbon fragment with general formula CnH2n+1
What is a saturated compound?
A compound that only contains single carbon-carbon bonds (C-C)
What is an unsaturated compound?
A compound that can contain carbon-carbon double bonds, triple bonds or aromatic groups
In structural isomers, the …. is the same, but the …. is different?
In structural isomers the molecular formula is the same, but the structural formula is different
What are the 3 types of structural isomers?
Chain isomers
Positional isomers
Functional group isomers
What is a chain isomer?
Where the carbon skeleton is arranged differently- as a straight chain or branched in different ways
What is the difference in chemical properties for chain isomers?
The chemical properties are the same
What is the difference in physical properties for chain isomers?
Physical properties (e.g. boiling point) are different because the shape of the molecule has changed
What are positional isomers?
A molecule with the same molecular formula as another molecule, but with the functional group in a different position
Describe the chemical and physical property differences for positional isomers
They have different chemical and physical properties
What are functional group isomers?
A molecule with the same molecular formula as another molecule, but with atoms arranged in different functional groups
Describe the chemical and physical property differences for functional group isomers
The physical and chemical properties are very different
What is the general formula for alkanes?
CnH2n+2
What is a hydrocarbon?
A molecule that contains only Hydrogen and Carbon
Are alkanes saturated or unsaturated?
Saturated, as they contain only carbon-carbon single bonds
What is a cycloalkane?
A type of alkane with one or more non-aromatic carbon rings
What is the agreed system for naming organic compounds?
IUPAC
What does IUPAC stand for?
International Union of Pure and Applied Chemistry
When was the IUPAC set up?
1919
Why was the IUPAC set up?
The aim was to create internationally accepted standards in Chemistry so that research could be shared more easily around the world
How many carbons does Meth- have?
1
How many carbons does Eth- have?
2
How many carbons does Prop- have?
3
How many carbons does But- have?
4
How many carbons does Pent- have?
5
How many carbons does Hex- have?
6
How many carbons does Hept- have?
7
How many carbons does Oct- have?
8
How many carbons does Non- have?
9
How many carbons does Dec- have?
10
When naming organic compounds, what has the suffix -‘ol’?
Alcohols e.g. Methanol
When naming organic compounds, what has the prefix ‘Chloro-‘
Chloroalkanes e.g. Chloromethane
What are the 2 parts to the name of a straight-chain alkane?
- The stem has the name given for however many carbons there are e.g. 5 carbons = Pent-
- All have the ending ‘-ane’
What is the side chain prefix for 1 carbon atom?
Methyl
What is the side chain prefix for 2 carbon atoms?
Ethyl
What is the side chain prefix for 3 carbon atoms?
Propyl
What is the side chain prefix for 4 carbon atoms?
Butyl
What is the side chain prefix for 5 carbon atoms?
Pentyl
What is the side chain prefix for 6 carbon atoms?
Hexyl
How do you name branched alkanes?
Count the longest chain of carbon atoms and then work out what side chains there are
In an alkane, what is the shape and bond angle around each carbon atom?
Tetrahedral, 109.5°
Why is the shape around a carbon atom tetrahedral?
Because there are 4 pairs of bonding electrons, so they all repel each other equally
What is a sigma (σ) bond
A bond formed when 2 orbitals overlap directly between the bonded atoms
How do covalent bonds form?
They can form between 2 atoms if they’re arranged so that the outer atomic orbitals overlap
What determines the strength of a sigma bond?
How well the orbitals overlap
Why do σ bonds have a high bond enthalpy?
Because The high electron density between the nuclei means there is a high electrostatic force of attraction between the nuclei and the shared pair of electrons
What is the strongest type of covalent bond?
σ-bonds
Are alkanes reactive or unreactive?
Unreactive
What are the 2 reasons why alkanes are unreactive?
- The C-C and C-H σ-bonds have a large bond enthalpy, so take a lot of energy to break
- The bonds are non-polar, so they won’t attract any positively or negatively charged particles to react with them
Describe the trend in boiling points with increasing sizes alkanes
The boiling point increases
Why does the boiling point of alkanes increase as they become longer?
Between the molecules are London forces. When the carbon chain gets longer the London forces increase so it takes more energy to overcome them
Why does the strength of the London forces increase with a longer carbon chain?
Because the alkane has a larger molecular surface area so there is more surface contact between the molecules and there are more electrons to interact with
Describe why the boiling point increases for the first 6 alkanes
As the alkane gets longer, the number of electrons in the molecules and the surface contact between molecules increases. So the London forces are stronger, taking more energy to overcome