Inside this lesson, you’ll find clear definitions, patterns you can remember instantly, exam-focused notes, and quick examples that bring the topic to life. Whether you're revising at midnight or prepping for a test tomorrow, this page is your shortcut to mastering functional groups with confidence.
Functional Groups
Definition
The functional groups are centers of chemical reactivity. Compounds having a similar functional group have undergone similar reactions. The presence of functional groups enables the systematization of organic compounds into different classes. The functional groups determine the way the molecule works both chemically and biologically.
An atom or a specific group of
atoms within the molecule which is responsible for unique chemical properties
and determines its characteristic reactions properties unique to that group is
called Functional Group. It is the site of chemical reactivity of organic
compounds.
OR
An atom or group of atoms which
is present within the organic molecule and is responsible for its chemical
behaviour and characteristic properties is called Functional Group.
A functional group is an active part of an organic molecule and serves as site of the reaction. Each functional group has its own chemical characteristic. Hence all the compounds containing the same functional group behave alike and belong to the same family or class.
The unique structural features of functional group makes it possible to classify organic compounds into limited number of groups or classes or homologous series. For example, alcohol is a class of organic compounds and all the members of this class contain –OH group as functional group.
Explanation
1. A functional group is an atom or group of atoms, double or triple bonds whose presence imparts specific properties to organic compounds. It gives specific and characteristic properties to an organic molecule.
2. They are chemically functional part of organic molecule. The hydrocarbon part i.e. alkyl group of the molecule is usually inert, the reactivity is due to functional group. Hence it is called active part. the remainder hydrocarbon part (alkyl group) of the molecule has an effect on its physical properties.
3. The functional group determines the basic
chemistry of an organic
compound.
For Example
(i) In alcohols (R–OH),
the hydroxyl group (–OH) is functional group.
(ii) In alkyl halide (R–X), the halide group (–X) is functional group.
Characteristics of functional groups
1. Each
functional group defines an organic family.
2. Each
functional group undergoes characteristic
reaction.
3. Functional
group helps us to name the organic compounds.
4. All the
compounds with the same functional group
belong to the same class.
5. Molecules can
contain more than one functional group called poly-functional
compounds.
6. One
functional group can modify the properties of other
functional groups.
Types of Functional groups
1. Non-terminating FG; (without C-containing
FG)
2. Terminating FG; (C-containing FG)
1. Non-terminating FG; (without
C-containing FG)
2. terminating
FG; (with C-containing FG)
Common and Important Functional Groups
Only alkanes are devoid
of any functional group. All other families possess a characteristic functional
group:
1. Olefinic Double Bond
Olefinic double bond (i.e. carbon-carbon
double bond) is the functional group of alkenes
or olefins or alkylenes.
e.g.
(i) Ethene or Ethylene (C₂H₄); H₂C=CH₂(ii) Propene or Propylene (C₃H6); CH₃–CH=CH₂
(iii) Butenes or Butylene (C₄H₈); (3 isomers or 4 isomers including stereoisomers)
2. Acetylenic Triple Bond
Acetylenic triple bond (i.e. carbon-carbon triple bond) is the functional group of alkynes or acetylenes. e.g.
(i) Ethyne or Acetylene, C₂H₂………………………........ HC≡CH(ii) Propyne or Allylene or methyl acetylene, C₃H₄…….. CH₃–C≡CH
(iii) but-1-yne or ethyl ethyne or ethyl acetylene, C₄H₆……. CH₃–CH₂–C≡CH
(iv) but-2-yne or crotonylene or dimethyl acetylene, C₄H₆….... CH₃–C≡C–CH₃ (2 isomers)
3. Halide Group
Halide group (–X) is the functional group of two series of organic compounds i.e. alkyl halide (R–X) and aryl halide (C6H5–X) where X represents Cl, Br and I.
(a) Halide Group (Alkyl Halides)
the series of organic compounds in which halide
functional group or halogen atom is attached directly to aliphatic (open chain)
carbon atoms are called alkyl halides denoted by R-X where ‘X’ may be F, CI, Br or I. alkyl halides are
mono-halogen derivative of alkane.
The halide functional group is of three
types:
(b) Aryl Halides
It is the series of organic compounds in
which –X atom is directly attached to carbon atom of benzene ring. e.g.
4. Hydroxyl Group
It is the functional group of two series i.e. alcohols and phenols.
(a) Alcoholic Hydroxyl Group for Alcohols
In alcohols, –OH is directly attached to aliphatic (open chain) carbon atoms. There are 3 types of alcohols:
(i) primary (1°) alcohols; (–CH₂–OH) e.g. CH₃–OH, CH₃–CH₂–OH(ii) secondary (2°) alcohols; (>CH–OH) e.g. (CH₃)₂–CH–OH (2°–propyl alcohol/isopropyl alcohol)
(iii) tertiary (3°) alcohols; (–>C–OH) e.g. (CH₃)₃.C–OH (3°–butyl alcohol)
1. primary Alcohols
Primary alcohols are those alcohols where the carbon atom of the hydroxyl group (OH) is attached to only
one single alkyl group. Some examples of these primary alcohols
include ethanol, propanol etc.
The complexity of this alkyl chain is unrelated to the
classification of any alcohol considered as primary. The existence of only one
linkage among –OH group and an alkyl group and the thing that qualifies any
alcohol as a primary.
2. secondary Alcohols
Secondary alcohols are those where the carbon
atom of the hydroxyl group is attached
to two alkyl groups on either side. The two alkyl groups
present may be either structurally identical or even different. Some examples
of secondary alcohols are given below.
3. tertiary Alcohols
Tertiary alcohols are those which feature hydroxyl
group attached to the carbon atom which is connected to three alkyl groups. The examples of tertiary
alcohols include:
Summary of Hydroxyl Group
Nature of FG-------------- Non-terminating FG, oxygen-containing FG, Univalent FG
Suffix of FG ---------------- ‘ol’
Prefix of FG --------------- Hydroxy
Class Name --------------- Alcohol
IUPAC Name -------------- alkanols
Common Name ---------- 1o or 2o or 3o Alkyl Alcohol
Type formula ------------- ROH or R–OH (R is any alkyl group)
General formula --------- Câ‚™H₂â‚™₊₁–OH (n = 1, 2, 3, 4……)
Condensed formula ----- Câ‚™H₂â‚™₊₂O (n = 1, 2, 3, 4……)
isomeric with ------------- Ether
Sub-types --------3, Primary alcoholic (–CH₂–OH, secondary alcoholic (>CH–OH), tertiary alcoholic (–>C–OH)
Examples -------------- H₃C–OH (Methyl alcohol), H3C–CH₂–OH (Ethyl alcohol)
Sub-types of Alcoholic Hydroxyl Group
Primary Alcoholic Group
Formula of
FG --------- –CH₂–OH
Class Name
------------- Primary Alcohol
Type
formula ---------- RCH₂–OH (R is any alkyl group)
Examples---------------- CH3OH (methyl alcohol), C2H5OH (ethyl alcohol), CH₃CH₂OH (primarypropyl alcohol)
Secondary Alcoholic Group
Formula of
FG --------- >CH–OH
Class Name
------------- Secondary Alcohol
Type
formula ---------- R₂CH–OH (R is any
alkyl group)
Examples---------------- (CH₃)₂CHOH (sec-propyl alcohol or iso-propyl alcohol)
Tertiary Alcoholic Group
Formula of FG --------- –>C–OH
Class Name
------------- Tertiary Alcohol
Type
formula ---------- R3C–OH (R
is any alkyl group)
Examples----------------
(CH₃)₃COH (Tertiary-butyl alcohol)
(b) Phenolic Hydroxyl Group for Alcohols
In phenol, –OH group is directly attached to
the carbon atom of a benzene ring.
5. Amino Group
Amino group is the functional group of amine. The organic compounds containing carbon, hydrogen and nitrogen as functional group are called as amines and functional group –NH₂ is called Amino Group. They are of 3 types:
(i) Primary amines; (–NH₂); e.g. CH₃–NH₂ (methyl amine), CH₃–CH₂–NH₂ (ethyl amine)(ii) Secondary amines; (>NH) ; e.g. (CH₃)₂.NH (dimethyl amine)
(iii) Tertiary amine; (–>N) ; e.g. (CH₃)₃.N (trimethyl amine)
There is a little difference in
the way amines are classified! Unlike the previous cases, the amines are
classified based on the number of carbons connected to the nitrogen. Another
difference with the amines is that the nitrogen can have four groups connected
by using the lone pair and getting a positive formal charge. These are called quaternary
ammonium salts.
6. Ether Linkage
The linkage of two carbon atoms through an oxygen atom is called an Ether linkage (C–O–C). It is the functional group of ether family. e.g.
(i) CH₃–O–CH₃; (dimethyl ether /Methoxymethane)(ii) C₂H₅–O–CH₃; (ethyl methyl ether/Methoxyethane)
(iii) C₂H₅–O–C₂H₅; (diethyl ether/Ethoxyethane)
7. Epoxide Group
In this group, two carbon atoms are directly bonded to each other through an oxygen atom. It is the functional group of alkanepoxides or alkyl oxirane or alkylene oxide
8. Thiol or mercapto (–SH)
It is the functional group of mercaptan or thiol or alkanethiol. Its type formula is RSH.
e.g.(ii) C₂H₅–SH; ethanethiol
9. Sulphonic acid group
It is the functional group of sulphonic acids. Its type formula is R–SO₃H.
e.g.(i) CH₃–SO₃H; methane Sulphonic acid
(ii) C₂H₅–SO₃H; ethane Sulphonic acid
10. Carbonyl Group
Carbon–oxygen double bond i.e. carbonyl group is the functional group of aldehydes and ketones.
(a) Ketones; (>C=O)
It is the series of organic compounds in which carbonyl group is directly linked to two carbon atoms of alkyl radicals.
e.g.(i) H₃C–CO–CH₃ (Acetone or Propanone or dimethyl ketone)
(ii) C₂H₅–CO–CH₃ (2-butanone/ethyl methyl ketone)
(b) Aldehydes; (–CHO)
It is the series of organic compounds in
which carbonyl group or Carbon–oxygen double bond (>C=O) is directly linked to
at least one hydrogen atom (except formaldehyde).
e.g.
Common Names
of First 20
Members of Aldehydes
Root
Words or Prefixes Used for First 20 Members of Aldehydes
Carboxyl group is the combination of a
carbonyl group (>C=O ) and a hydroxyl group (–OH)
i.e. –CO–OH or –COOH. Carboxyl group is
the functional group of carboxylic acids. Compounds
containing the carboxylic functional group; HO>C=O or –COOH are
called carboxylic acids. They have the general formula RCOOH where R stands for
–H or any alkyl groups.
derivatives functional groups of carboxyl
groups
Following
are the derivatives functional groups of carboxyl groups:
(a) Ester Group (–COO–R)
(b) Acid Amides (–CONH₂)
(c) Acid Halides (–CO–X)
(d)
Acid anhydride (–CO–O–CO–)
(e)
Nitrile group (–CN or –C≡N)
(f)
Isonitrile group (–NC or –N+≡C⁻)
(a) Acid Halides/Halocarbonyl/oylhalide (–CO–X)
The replacement of hydroxyl group from a
carboxyl group by a halogen atom gives an acid halide group. If the acid
is a carboxylic acid (−C(=O)OH),
the compound contains a −C(=O)X functional group, which consists of a carbonyl group (C=O) singly bonded to
a halogen atom. It is the functional group of acid halides/Alkanoyl halide.
Summary
Formula of FG ------------------------ –COX
Nature
of FG -------terminating
FG, Both C and halogen-containing FG, Univalent FG
Class
or Family Name ------------ Acid
halides
IUPAC
name of family ----------- Alkanoyl halide
Common
name of family ------- Acyl halide or carboxyl halide
Suffix
of FG ------------------------- oyl halide
Prefix
of FG ------------------------- halocarbonyl
Type
formula of family ---------- R'COX
(R' is H or any alkyl group)
General
formula of family ------ Câ‚™H₂â‚™₊₁– COX (n = 0, 1, 2, 3, 4……)
Examples----H–COCl,CH₃–COCl(Acetylchloride/Ethanoyl Chloride )
(b) Acid Amides or Amide (–CONH₂)
The replacement of hydroxyl group from a carboxyl group by an amino group gives an amide group. It is the functional group of alkanamide family. It can be viewed as a derivative of a carboxylic acid (R−C(=O)−OH) with the hydroxyl group (−OH) replaced by an amine group (−NR′R″); or, equivalently, an acyl (alkanoyl) group (R−C(=O)−) joined to an amine group.
Summary
Formula of FG --------------------- –CONH₂
or –CONH– or –CON<
Nature
of FG -----Non-terminating
FG, Both C, N and oxygen-containing FG, Univalent FG
Suffix
of FG ------------------------- amide
Prefix
of FG ------------------------- amido
Class
or Family Name -----Amides or Acid Amide or Carboxamide
IUPAC
name of family ----------- Alkanamide
Common
name of family ------- Carboxamide
Type formula
of family ---------- R'CONH₂ or
R–CONH–R or R–CONR₂ (R' is H or any alkyl group)
General
formula of family -----Câ‚™H₂â‚™₊₁–CONH₂
(n = 0, 1, 2, 3, 4……)
Examples-----------H–CONH₂ (Formamide/Methanamide),CH3–CONH₂ (Acetamide/Ethanamide)
Types of Amides
Like amines, the amides are classified as primary, secondary and
tertiary based on the number of carbons connected to the nitrogen.
(c) Ester Group/Ester
Linkage (–COO–R)
The replacement of hydrogen of hydroxyl group from a carboxyl group by an alkyl group (–R) gives an ester group (RO>C=O or –COOR). It is the functional group of esters. Organic compounds containing the functional group; RO>C=O or –COOR are called esters. They have the general formula RʹCOOR where Rʹ stands for –H or any alkyl groups.
Summary
Formula of FG --------------------- –COOR
Nature
of FG -----Non-terminating
FG, Both carbon and oxygen-containing FG, Bivalent FG
Suffix
of FG ------------------------- oate
Prefix
of FG ------------------------- oxycarbonyl
Class
or Family Name ------------ Esters
IUPAC
name of family ----------- Alkyl
alkanoate
Common
name of family ------- Alkyl
carboxylate
Type
formula of family ---------- R'COOR (R' is H
or any alkyl group; may be same or different)
General
formula of family ------ Câ‚™H₂â‚™₊₁–COOR
(n = 0,1, 2, 3, 4……)
Condensed
General formula---- Câ‚™H₂â‚™O2 (n = 2, 3, 4…) (isomeric with
carboxylic acids)
Isomeric
with ----------------------
carboxylic acids
Examples-------H–COO–CH₃ (Methyl formate/methyl methanoate), CH₃–COO–CH₃
(Methyl acetate/ methyl
ethanoate), CH₃–COO–C₂H₅ (Ethyl acetate/ethyl ethanoate)
(d) Carboxylic acid
anhydride/Acid anhydride group; (–CO–O–CO–)
An acid
anhydride is a type of chemical compound derived by the removal of water molecules
from an acid. Acid anhydride group
is the functional group of acid anhydride family. In organic chemistry, organic
acid anhydrides contain
the functional
group −C(=O)−O−C(=O)− or –CO–O–CO–. Organic acid anhydrides often form when one equivalent of water is removed from two equivalents of
an organic
acid in a dehydration
reaction.
Acid anhydrides contain two acyl groups and have the general formula RC(=O)OC(=O)R or acyl—O—acyl. The acyl groups may be the same (symmetric) or different (asymmetric or mixed). The simplest and most common acid anhydrides are symmetrical derivatives of monobasic acids.
Summary
Formula of FG --------------------- −C(=O)−O−C(=O)−
or –CO–O–CO–
Nature
of FG ------terminating FG, Both carbon and oxygen-containing FG,
Bivalent FG
Suffix
of FG ------------------------- oic anhydride
Prefix
of FG ------------------------- alkanoyloxycarbonyl
Class
or Family Name ------------ Acid anhydride
IUPAC
name of family ----------- Alkanoic
anhydride
Common
name of family ------- Carboxylic
anhydride
Type
formula of family ---------- RC(=O)OC(=O)R or –CO–O–CO– (R' is
H or any alkyl group; may be same or different)
General
formula of family ------ Câ‚™H₂â‚™₊₁–COCOR
(n = 0,1,2,3, 4…)
Examples --------H–CO–O–CO–H
(Formic anhydride/Methanoic anhydride),CH₃–CO–O–CO–CH₃(Aceticanhydride/ethanoic anhydride), CH₃–CO–O–CO–
CH₃ (Benzoic anhydride)
(e)
Cyanide or Nitrile group (–CN or –CºN)
The functional group −C≡N is called nitrile or cyano which is the functional group of alkanenitrile family.
Summary
Formula
of FG --------------------- –CN or –C≡N
Nature of FG ------terminating
FG, Both carbon and nitrogen-containing FG, Univalent FG
Suffix of FG ------------------------- nitrile
Prefix of FG ------------------------- cyano or carbonitrile
Class or Family Name ------------ Nitriles
IUPAC name
of family ----------- Alkanenitrile
Common name
of family ------- Cyanoalkane
Type formula of family ----- R–CN or R–C≡N (R is any alkyl group)
General formula of family ------ Câ‚™H₂â‚™₊₁–CN (n = 1, 2,
3, 4……)
Examples -------------------------CH₃–CN (ethanenitrile), CH₃–CH₂–CN (Propanenitrile), C₆H₅–CN (Benzonitrile)
(f) Isocyanide or Isonitrile or
Carbylamine (–NC or –N≡C⁻)
It is the functional group of
alkaneisonitrile family.
e.g.
(i) CH3–NC––––– ethaneisonitrile
(ii) C2H5–NC––––
propaneisonitrile
**✨ QUIZ SECTION
( Attempt First — Answers Below)**
Quiz 1
Identify the functional group:
CH₃–CH₂–OH
🟥 A. Alcohol
🟦 B. Aldehyde
🟩 C. Alkane
🟨 D. Ketone
Quiz 2
Which compound belongs to the ketone family?
🟥 A. Ethanol
🟦 B. Propanone
🟩 C. Ethanal
🟨 D. Ethyne
Quiz 3
Which functional group is present in amino compounds?
🟥 A. –COOH
🟦 B. –OH
🟩 C. –NH₂
🟨 D. –CHO
Quiz 4
General formula of alkenes is:
🟥 A. Câ‚™H₂â‚™₊₂
🟦 B. Câ‚™H₂â‚™
🟩 C. Câ‚™H₂â‚™₋₂
🟨 D. Câ‚™H₂â‚™O₂
Quiz 5
Which of the following is a carboxylic acid?
🟥 A. Ethanoic acid
🟦 B. Methanol
🟩 C. Propanal
🟨 D. Propene
✔ QUIZ ANSWERS
1. A2. B
3. C
4. B
5. A
🌈 Functional Groups MCQs Quiz 2🧪
🟥 1. Which functional group is present in aspirin (acetylsalicylic acid)?
🟦 A. Aldehyde
🟩 B. Ester
🟨 C. Amine
🟪 D. Ketone
🟥 2. The functional group –CONH₂ is called:
🟦 A. Amide
🟩 B. Nitrile
🟨 C. Carboxylic acid
🟪 D. Ether
🟥 3. Which of the following compounds contains a sulfonic acid group?
🟦 A. CH₃SO₃H
🟩 B. CH₃OH
🟨 C. CH₃COOH
🟪 D. CH₃NH₂
🟥 4. The compound CH₃CH₂CHO belongs to which functional group?
🟦 A. Alcohol
🟩 B. Aldehyde
🟨 C. Ketone
🟪 D. Ether
🟩 B. Alcohol
🟨 C. Haloalkane
🟪 D. Nitrile
🟥 6. Which functional group is present in acetamide (CH₃CONH₂)?
🟦 A. Amide
🟩 B. Amine
🟨 C. Ester
🟪 D. Aldehyde
🟥 7. In which functional group is a carbon double bonded to oxygen and single bonded to OH?
🟦 A. Carboxylic acid
🟩 B. Ketone
🟨 C. Ester
🟪 D. Amine
🟥 8. CH₃CH₂OH is an example of:
🟦 A. Aldehyde
🟩 B. Alcohol
🟨 C. Ketone
🟪 D. Carboxylic acid
🟥 9. Which functional group contains a carbon-nitrogen triple bond?
🟦 A. Amine
🟩 B. Nitrile
🟨 C. Imine
🟪 D. Amide
🟥 10. The functional group –COOR represents:
🟦 A. Ester
🟩 B. Ether
🟨 C. Ketone
🟪 D. Amide
🟥 11. Phenol contains which functional group?
🟦 A. Alcohol
🟩 B. Ether
🟨 C. Hydroxyl attached to aromatic ring
🟪 D. Carboxylic acid
🟥 12. Which compound has a carbonyl group within the carbon chain?
🟦 A. CH₃CH₂CHO
🟩 B. CH₃COCH₃
🟨 C. CH₃CH₂OH
🟪 D. CH₃COOH
🟥 13. Which functional group is acidic in nature?
🟦 A. Alcohol
🟩 B. Carboxylic acid
🟨 C. Ketone
🟪 D. Amine
🟥 14. Which functional group contains a nitrogen atom bonded to two hydrogen atoms?
🟦 A. Primary amine
🟩 B. Secondary amine
🟨 C. Amide
🟪 D. Nitrile
🟥 15. Which of the following contains a carbon-oxygen double bond but no OH?
🟦 A. Aldehyde
🟩 B. Ketone
🟨 C. Both A and B
🟪 D. Ester
🟥 16. The functional group –SH is called:
🟦 A. Hydroxyl
🟩 B. Sulfhydryl
🟨 C. Thioether
🟪 D. Thioketone
🟥 17. Which functional group is present in methylamine (CH₃NH₂)?
🟦 A. Amine
🟩 B. Amide
🟨 C. Nitrile
🟪 D. Imine
🟥 18. CH₃COOCH₃ is an example of:
🟦 A. Ester
🟩 B. Ether
🟨 C. Alcohol
🟪 D. Ketone
🟥 19. Which functional group has the general formula R–CO–R’?
🟦 A. Ketone
🟩 B. Aldehyde
🟨 C. Ester
🟪 D. Amide
🟥 20. Which functional group is present in amino acids?
🟦 A. Amino and carboxyl
🟩 B. Alcohol
🟨 C. Aldehyde
🟪 D. Ketone
✅ Functional Groups MCQs Answers – Check Your Score! 🧪
Here are the answers for the 20 functional group quizzes:
-
🟩 B. Ester
-
🟥 A. Amide
-
🟥 A. CH₃SO₃H (Sulfonic acid)
-
🟦 B. Aldehyde
-
🟩 B. Alcohol
-
🟥 A. Amide
-
🟥 A. Carboxylic acid
-
🟩 B. Alcohol
-
🟩 B. Nitrile
-
🟥 A. Ester
-
🟨 C. Hydroxyl attached to aromatic ring
-
🟩 B. CH₃COCH₃ (Ketone)
-
🟩 B. Carboxylic acid
-
🟦 A. Primary amine
-
🟨 C. Both A and B
-
🟩 B. Sulfhydryl
-
🟦 A. Amine
-
🟦 A. Ester
-
🟦 A. Ketone
-
🟦 A. Amino and carboxyl
🚀 Top Functional Groups MCQs for MDCAT – Test Your Skills! Quiz 3 🧪
MCQ 1
Which functional group is
present in alcohols?
🟥 A. –OH
🟦 B. –COOH
🟩 C. –CHO
🟨 D. C=C
Answer: A. –OH
MCQ 2
Which compound contains the
aldehyde group?
🟥 A. Methanal
🟦 B. Methanol
🟩 C. Methane
🟨 D. Methylamine
Answer: A. Methanal
MCQ 3
Functional group of
carboxylic acids is:
🟥 A. –COOH
🟦 B. –CO–
🟩 C. –NH₂
🟨 D. –OH
Answer: A. –COOH
MCQ 4
Which of the following is a
ketone?
🟥 A. Propanone
🟦 B. Propanol
🟩 C. Propanal
🟨 D. Propene
Answer: A. Propanone
MCQ 5
Which functional group
defines amines?
🟥 A. –NH₂
🟦 B. –OH
🟩 C. –CHO
🟨 D. C≡C
Answer: A. –NH₂
MCQ 6
Which of the following is
an alkene?
🟥 A. Ethene
🟦 B. Ethyne
🟩 C. Ethanol
🟨 D. Ethane
Answer: A. Ethene
MCQ 7
General formula of alkanes
is:
🟥 A. Câ‚™H₂â‚™₊₂
🟦 B. Câ‚™H₂â‚™
🟩 C. Câ‚™H₂â‚™₋₂
🟨 D. Câ‚™H₂â‚™O
Answer: A. Câ‚™H₂â‚™₊₂
MCQ 8
Which functional group is
present in ketones?
🟥 A. –CO– (carbonyl)
🟦 B. –COOH
🟩 C. –OH
🟨 D. –NH₂
Answer: A. –CO–
MCQ 9
Which compound contains a
triple bond?
🟥 A. Ethyne
🟦 B. Ethane
🟩 C. Ethanol
🟨 D. Propanol
Answer: A. Ethyne
MCQ 10
Functional group of
aldehydes is:
🟥 A. –CHO
🟦 B. –CO–
🟩 C. –NH₂
🟨 D. –OH
Answer: A. –CHO
🌈 Functional Groups Tricks & Tips for MDCAT/ECAT Success🧪
1. Learn Functional Groups by “Families”
📌Alcohols & Phenols: –OH group
📌 Aldehydes & Ketones: C=O group
📌 Carboxylic acids & Derivatives: –COOH, –COOR, –CONH₂
📌Amines & Amides: –NH₂, –CONH₂
📌Nitriles & Sulfur Compounds: –C≡N, –SH
Tip: Grouping makes it easier to recall reactions and properties.
2. Use Mnemonics
📌Alcohol → “OH yes I can!” → all have –OH
📌Carboxylic acids → “COOH is acidic” → remember acidity
📌Aldehyde vs Ketone: Aldehyde = at the end (H attached), Ketone = middle (two carbons)
3. Identify by Structure
📌Quickly spot C=O → aldehyde/ketone/acid/ester/amide📌Spot –OH attached to aromatic → phenol
📌 Spot C≡N → nitrile
📌Spot –SH → thiol
4. Common Reactions as Clues
📌 Tollens’ test (Ag mirror): Aldehydes → turns silver
📌 Fehling’s/Benedict’s test: Aldehydes → red precipitate
📌 NaHCO₃ reaction: Carboxylic acids → produce CO₂
Tip: Reaction hints in MCQs often indicate the functional group.
5. Memorize Key Properties
📌Acidity/Basicity:
⚡Carboxylic acid → acidic
⚡Phenol → weakly acidic
⚡Amine → basic
📌 Solubility: Small alcohols/ acids → water-soluble, large chains → less soluble
6. Quick Elimination Technique in MCQs
📌 If you see: C=O + H at the end → aldehyde
📌 If you see: C=O + OH → acid
📌 If you see: C=O + OR → ester
📌 If you see: C=O + NH₂ → amide
Tip: Use “structure clues” to eliminate wrong options fast.
7. Functional Group Pairs
📌 Often, MDCAT tests comparisons: e.g., acidity of alcohol vs phenol.
📌 Remember: COOH > Phenol > Alcohol > Amine (acid strength)
8. Shortcut for Names
📌 Alcohol = –ol, Aldehyde = –al, Ketone = –one, Carboxylic acid = –oic acid, Ester = –oate, Amide = –amide, Nitrile = –nitrile, Thiol = –thiol
Tip: If options have name clues, match with suffix.
9. Practice Recognition
📌 Draw small molecules and label the functional groups.
📌 Use color coding (e.g., red for oxygen, blue for nitrogen, yellow for sulfur) to remember visually.
10. Use Past Papers
📌Functional group MCQs are repetitive.
📌Identify tricky patterns: “Which functional group is more acidic?”, “Which reacts with NaHCO₃?”, “Which gives silver mirror?”
💡 Extra Hack: Make a one-page “Functional Groups Table”:
| Functional GroupGeneral FormulaKey TestPropertiesExample |
|---|
This acts as a last-minute revision tool before MDCAT.
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