Introduction to Organic Chemistry Flashcards
Define empirical formula
The simplest whole number ratio of atoms of each element in a compound.
Define molecular formula
The actual number of atoms of each element in a compound.
Define homologous series.
A family of organic compounds that have the same functional group. They have the same general formula and similar chemical properties.
What so consecutive members of a homologous series differ by?
-CH2-
In a homologous series, the length of the carbon chain changes. What effects does this have on the chemical or physical properties of the molecule?
- Has little effect on the chemical reactivity.
- Increasing C chain length increases the melting and boiling points and decreases solubility because the IMFs increase.
Why does chain branching reduce melting points?
Because the molecules can’t pack together as closely.
What is the general formula for alkanes?
CnH2n+2
What is the general formula for alkenes?
CnH2n
What is the general formula for alcohols?
CnH2n+1OH
What is the general formula for cycloalkanes?
CnH2n
What is the general formula for branched alkanes?
CnH2n+2
What is the general formula for aldehydes?
R-CHO, where R is an alkyl group or H atom
What is the general formula for ketones?
R-C=O-R’
Where R and R’ are alkyl groups (may or may not be the same), NOT an H atoms because that would make it an aldehyde
What is the general formula for carboxylic acids?
R-COOH
R= alkyl group or H atom
Define functional group
An atom or group of atoms in an organic molecule which is responsible for the characteristic reactions of that molecule.
Define structural isomers.
Molecules with the same molecular formula, but a different structural formula
What are the 3 different types of structural isomers?
- Chain isomers- different arrangement of carbon skeleton
- Position isomers-the position of the functional group on the carbon chain changes
- Functional group isomers- same atoms are arranged into different functional groups
Define stereoisomers
Molecules with the same structural formula, but a different arrangement of atoms in space
what type of isomerism is E/Z isomerism?
Stereoisomerism
Give 2 types of stereoisomerism
- E/Z
- Optical
What is the shape of a C=C bond and the atoms bonded to this C?
Planar, 120 degrees bond angle
Why does E/Z isomerism occur?
As a result of restricted rotation about the planar C=C double bond.
What are the Cahn-Ingold-Prelog (CIP) priority rules?
- Assign a priority to the 2 atoms attached to each side of the double bond.
- Atom with the higher atomic number on each carbon is given the higher priority
- If the atoms directly bonded to each carbon are the same, then you look at the next atom in the groups to work out which has the higher priority
- To work out which isomer you have, look at how the two highest priority groups are arranged. If they’re positioned across the double bond from each other, it’s the E isomer. Is they’re both above or below the double bond, it’s the Z isomer.
