Unit 4 - Lesson 9: Naming and Grouping Organic Compounds Flashcards
What is organic chemistry?
The study of organic compounds (compounds that contain carbon).
What does organic chemistry NOT include?
CO2, CO, carbonates, and hydrogencarbonates.
What are organic compounds structure-wise?
They’re chains, branched chains, or carbon rings with hydrogens attached.
What are compounds grouped by?
Their functional group.
Compounds are grouped by their functional group. What are groups called?
Homologous series.
What is a functional group?
A functional group is an atom or group of atoms that all compounds in a homologous series share.
What do functional groups determine for a compound and therefore what does this mean that all compounds in a homologous series share?
Functional groups determine the chemical properties of a compound. Therefore, all compounds in a homologous series share the similar chemical properties.
What do functional groups show a trend in/share?
Physical properties.
There are five homologous series. What are they?
Alkanes.
Alkenes.
Alcohols.
Carboxylic Acids.
Esters.
What are alkanes? Why does this mean some people consider them not to have a functional group?
Alkanes are hydrocarbon chains, so some people consider them not to have a functional group (an atom/group of atoms that all compounds in a homologous series share).
What is the functional group of the homologous series: Alkenes?
C = C
Draw the displayed formula for the homologous series: Alkenes.
https://i.pinimg.com/736x/4a/78/d9/4a78d98f8b2372faa30f2f4168d5041f.jpg
What is the functional group of the homologous series: Alcohols?
O - H
Draw the displayed formula for the homologous series: Alcohols.
R - O - H
What is the functional group of the homologous series: Carboxylic Acids?
https://i.pinimg.com/736x/b1/ff/47/b1ff47cd300858d39c21c997131643cf.jpg
Draw the displayed formula for the homologous series: Carboxylic Acids.
https://i.pinimg.com/736x/3b/5c/17/3b5c17a4be433c842a9a0cc502463b5d.jpg
What is the functional group of the homologous series: Esters?
https://i.pinimg.com/736x/17/88/a8/1788a82be4dcac2eddf988a91be23231.jpg
Draw the displayed formula for the homologous series: Esters.
https://i.pinimg.com/736x/67/0a/73/670a7363c5ba33ccf4081e2c9231e342.jpg
What is a general formula for an organic compound?
The general formula can be thought of as the blueprint for writing all the members of a homologous series.
What is the general formula for alkenes?
CnH2n
The general formula for alkenes is CnH2n.
a) How many hydrogen atoms are there per carbon?
b) What does the letter ‘n’ represent?
c) Butene is an alkene. How many carbons and hydrogens does butene have?
a) There are 2 hydrogens per carbon.
b) The letter ‘n’ represents the number of carbons.
c) Butene is an alkene with 4 carbons and 8 hydrogens (2 x n).
What is the general formula for alkanes?
CnH2n+2
The general formula for alkanes is CnH2n+2.
a) What does the letter ‘n’ represent?
b) Butane has 4 carbons. Find how many hydrogens are in butane.
a) ‘n’ represents the number of carbons.
b) Butane has 4 carbons. C4H(2x4) + 2. Essentially, this is 2 x 4 + 2 = 10. There are 10 hydrogens.
What does the empirical formula give?
The empirical formula gives the simplest whole number ratio of the atoms present in a compound.
What does the molecular formula give?
The molecular formula gives the actual number and type of atoms in a compound. The molecular formula is always a whole number multiply of the empirical formula.
Why are molecular formulas and empirical formulas not often used in organic chemistry?
They don’t give information about structure/bonding.
How do we find the molecular formula from an empirical formula?
Example: A compound has an empirical formula C4H3O2. The Mr is 332 g. What is it’s molecular formula?
- Work out the mass of the empirical formula.
(4 x 12) + (3 x 1) + (2 x 16) = 83 g - Divide the experimental relative molecular mass (Mr) by the empirical mass from step 1.
332 / 83 = 4 - The molecular formula is the empirical formula multiplied by the value from step 2.
Empirical –> C4H3O2 Molecular –> C16H12O8
In three steps, how do we find the molecular formula from an empirical formula?
- Work out the mass of the empirical formula.
- Divide the experimental relative molecular mass (Mr) by the empirical mass from step 1.
- The molecular formula is the empirical formula multiplied by the value from step 2.
What do displayed formulas show?
All the bonds in a compound.
In displayed formulas, what functional group shows that the displayed formula is an alcohol?
-OH
In an exam, if you are asked to draw a molecule, what should you draw (unless asked otherwise)?
A displayed formula.
How do you write a structural formula from a displayed formula?
Start with the first carbon on the left, writing down each carbon and what it’s bonded to. If you can condense, further do so. In this case, we can condense to CH3(CH2)2CH3. This is a condensed structural formula.
https://i.pinimg.com/736x/6b/1a/d3/6b1ad398be4a92fe29afff35537f1d9c.jpg
Structural formulas in IGCSE are usually written in what shape?
Straight horizontal line.
What is the international language for chemistry (IUPAC)?
A set of rules for the nomenclature (naming) of organic compounds.
What does ‘nomenclature’ mean?
Naming. “The devising or choosing of names for things…”
What is the organic compound’s name’s prefix if it has:
a) 1 carbon
b) 2 carbon
c) 3 carbon
d) 4 carbon
e) 5 carbon
f) 6 carbon
a) Meth- (1 Carbon)
b) Eth- (2 Carbon)
c) Prop- (3 Carbon)
d) But- (4 Carbon)
e) Pent- (5 Carbon)
f) Hex- (6 Carbon)
What mnemonic helps you learn the first four prefixes in an ascending order?
Monkeys Eat Pink Bananas.
Meth-, Eth-, Prop-, But-
To remember the last two, remember that Pent means 5 and Hex means 6.
What is the suffix for alkanes?
-Ane
What is the suffix for alkenes?
-Ene
When naming your organic compound, you must see if the carbon chain has more than 2 carbons. If it does, then what number carbon is the functional group on? (EG. the functional group for alkenes is C=C) What do you do with this number?
Write that number down between the prefix and suffix.
For example, in Butene, the functional group (C=C) is on carbon 1, so the name is actually but-1-ene.
When naming your organic compound, you must see if the carbon chain has more than 2 carbons. If it does, then the number of the carbon that the functional group is on will be written in between the prefix and suffix (EG, but-1-ene). Sometimes counting from different ends of the carbon chain will mean the functional group is on a different carbon. Should you use the smaller or bigger number?
The smaller number.
When naming your organic compound, you must see if the carbon chain has more than 2 carbons. If it does, then the number of the carbon that the functional group is on will be written in between the prefix and suffix (EG, but-1-ene). However, if your organic compound is an alcohol, where should you write the number? Give an example.
For alcohols, write the number after the -an (the suffix being anol, and so separating the -an from the -ol). For example, the functional group on this alcohol is on carbon 2 (O-H). It is called propan-2-ol. Notice how after the prefix (prop-), I wrote -an, then the number, and then the rest of the suffix (-ol).
https://i.pinimg.com/736x/19/82/1e/19821e5406981b140a3a6a0b70aed70f.jpg
If there are only 1 or 2 carbons in the chain, what carbon must the functional group be on?
If there are only 1 or 2 carbons in the chain, the functional group can only be on carbon 1 so we don’t need to write in 1.
What are the two type of side chains you’re likely to see in your exam?
Methyl and ethyl.
What is the chemical formula for methyl?
CH3
What is the chemical formula for ethyl?
CH3CH2
If there is 1 side chain, what is the beginning of the compound’s name?
If there’s 1 side chain, there is not a specific beginning of name.
If there is 2 side chains, what is the beginning of the compound’s name?
Di
If there is 3 side chains, what is the beginning of the compound’s name?
Tri
If there is 4 side chains, what is the beginning of the compound’s name?
Tetra
Name this compound and explain why:
https://i.pinimg.com/736x/3a/54/67/3a54678b28614f9c48ab6f54ce719920.jpg
2-methylbutane
It has 4 carbons so it’s a butane.
It has 1 methyl group on carbon 2 so it’s called a 2-methylbutane.
Name this compound and explain why:
https://i.pinimg.com/736x/0d/66/89/0d66897ed226d33ac8f7581989fbdfe9.jpg
2,2-dimethylpropane
It has 3 carbons so is a propane.
It has 2 methyl groups both on carbon 2 so is called 2,2-dimethylpropane.
Name this compound and explain why:
https://i.pinimg.com/736x/c1/c7/60/c1c76059c8cf66890188cd05359ba579.jpg
2,3-dimethylbutane
It has 4 carbons so is a butane.
It has 2 methyl groups on carbon 2 and 3, so is called 2,3-dimethylbutane.
Some organic compounds have MULTIPLE functional groups. If there is more than one functional group, what do you write for:
(a) 2 functional groups
(b) 3 functional groups
(c) 4 functional groups
And
(d) Where do you write the number?
a) Di (for 2 functional groups)
b) Tri (for 3 functional groups)
c) Tetra (for 4 functional groups)
And
d) Between the pre- and -suffix.
If there are two C=C bonds in a 3 carbon chain, that is not called propene. What is it actually called due to it having multiple functional groups?
Propdiene. You’ll notice that I used the prefix “Prop” because there are 3 carbon. I used “di” in between the prefix and suffix because there are 2 functional groups. I used the suffix “ene” because it is an alkene.
If there are three C=C bonds in a 6 carbon chain, what is that organic compound called?
Hextriene.
The prefix “hex” is used because there are 6 carbon.
“Tri” is used because there are three functional groups.
The suffix “ene” is used because it is an alkene.
An organic compound is called “Propdiene”.
a) How many carbons are in this compound?
b) How many functional groups are in this compound?
c) What homologous series is this compound?
d) What is the functional group of this compound?
a) There are 3 carbons in this compound, hence the use of the prefix “Prop”.
b) There are 2 functional groups in this compound, hence the use of “Di”.
c) This compound is an Alkene, hence the use of the suffix “Ene”.
d) The functional group of this compound is C=C because it is an alkene.
How do you name organic compounds using a structural formula?
- Count the number of carbons in the main chain to find the prefix.
- The functional group gives the suffix.
- Give the carbon number the functional group is on (between the prefix and suffix), if not the first.
How do you draw the DISPLAYED FORMULA for, for example, 2,3-dimethylbut-2-ene?
- How many carbons are in the main chain? Write them out in a line. (‘But’ tells us there are 4).
C - C - C - C - What is the functional group? The ‘ene’ tells us this is an alkene, so the group is C=C.
- Where is the functional group? On carbon 2.
C - C = C - C - If there is a side chain? If so, what is it and how many are there? There are 2 methyl groups (dimethyl).
- Where is/are the side chain(s)? On carbons 2 and 3 (2,3).
- Does each carbon have 4 bonds? If not, add hydrogens until they do. This is the displayed formula.
https://i.pinimg.com/736x/75/38/96/753896d46632f042c9d75e32ea70f7ca.jpg
How do you draw the STRUCTURAL FORMULA for, for example, 2,3-dimethylbut-2-ene?
For the structural formula, remove all bonds, bar those linking the main carbon chain, any double bonds and links to side chains. You could remove all bonds, bar the double bonds and those linking to the side chains. Choose the right one for you.
https://i.pinimg.com/736x/24/a9/30/24a93036349c478721f97b6de580d0e8.jpg
