ChemistryChapter 19: Carbonyl Compounds
Aldehydes and Ketones
Both have the carbonyl C=O.
Learning objectives
- Explain aldehydes and ketones in simple chemical language.
- Connect 1. names with 2. bond using equations, observations, or trends where needed.
- Answer a short Federal Board question with the correct terms and a clear reason.
Definition
Both have the carbonyl C=O. Aldehyde: C=O at the end (CHO). Ketone: C=O in the chain. Ending -al vs -one. Planar carbon, polar C=O (C d+, O d-). Nucleophiles attack the carbon (later). Meaning: same group, different position — tests sort them (Tollens, Fehling). These notes are school carbonyls, not fragrance manufacture. Aldehyde CHO terminal; ketone C=O within chain — both have polar carbonyl. Tollens distinguishes aldehyde from ketone; iodoform targets methyl carbonyl or ethanol specifically.
Mathematical form
C=O. Aldehyde
C=O at the end (CHO). Ketone
C=O in the chain. Ending -al vs -one. Plan
C=O (C d+
Important terms
- ALDEHYDES AND KETONES
- Both have the carbonyl C=O.
- 1. NAMES
- Methanal, ethanal, propanone, pentan-3-one.
- 2. BOND
- C=O shorter/stronger than C-O, still polar.
Relationship
- ketone C=O middle
Overview
Structure, then polarity:
Names
Methanal, ethanal, propanone, pentan-3-one. Number the carbonyl lowest. Do not write -al for a ketone. Aldehyde oxidised easily to acid; ketone harder — distinction test basis.
Examples Ethanal · Propanone · Lowest number
Bond
C=O shorter/stronger than C-O, still polar. No H-bond donor unless you count the aldehyde H weakly; boiling points lower than alcohols of similar size (no OH-OH network). Nucleophilic addition to C=O — C delta+ attacked by Nu.
Examples Nu attacks C · b.p. vs alcohol · Planar 120 school
WHAT — ALDEHYDES AND KETONES
Both have the carbonyl C=O. Aldehyde: C=O at the end (CHO). Ketone: C=O in the chain. Ending -al vs -one. Planar carbon, polar C=O (C d+, O d-). Nucleophiles attack the carbon (later). Meaning: same group, different position — tests sort them (Tollens, Fehling). These notes are school carbonyls, not fragrance manufacture. Aldehyde CHO terminal; ketone C=O within chain — both have polar carbonyl. Tollens distinguishes aldehyde from ketone; iodoform targets methyl carbonyl or ethanol specifically.
WHY — Why this topic matters
ALDEHYDES AND KETONES is an independent FBISE learning unit because students must use its definitions, conditions, equations, or trends separately in explanations and calculations.
HOW — How it works
NAMES: Methanal, ethanal, propanone, pentan-3-one. Number the carbonyl lowest. Do not write -al for a ketone. Aldehyde oxidised easily to acid; ketone harder — distinction test basis. Examples: Ethanal; Propanone; Lowest number. BOND: C=O shorter/stronger than C-O, still polar. No H-bond donor unless you count the aldehyde H weakly; boiling points lower than alcohols of similar size (no OH-OH network). Nucleophilic addition to C=O — C delta+ attacked by Nu. Examples: Nu attacks C; b.p. vs alcohol; Planar 120 school. Exam pair: ethanal: aldehyde, CHO propanone: ketone, C=O in the chain both carbonyls; tests tell them apart
In simple words
Structures. No solvent or perfume plant.
Key points
- aldehyde CHO end
- ketone C=O middle
- suffix
- C d+
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Aldehydes and Ketones
Sticky Notes · Quick Revision
Core Idea
- Both have the carbonyl C=O. Aldehyde: C=O at the end (CHO). Ketone: C=O in the chain. Ending -al vs -one. Planar carbon, polar C=O (C d+, O d-). Nucleophiles attack the carbon (later). Meaning: same group, different position — tests sort them (Tollens, Fehling). These notes are school carbonyls, not fragrance manufacture. Aldehyde CHO terminal; ketone C=O within chain — both have polar carbonyl. Tollens distinguishes aldehyde from ketone; iodoform targets methyl carbonyl or ethanol specifically.
1. NAMES
- Methanal, ethanal, propanone, pentan-3-one. Number the carbonyl lowest. Do not write -al for a ketone. Aldehyde oxidised easily to acid; ketone harder — distinction test basis.
- Ethanal
- Propanone
- Lowest number
2. BOND
- C=O shorter/stronger than C-O, still polar. No H-bond donor unless you count the aldehyde H weakly; boiling points lower than alcohols of similar size (no OH-OH network). Nucleophilic addition to C=O — C delta+ attacked by Nu.
- Nu attacks C
- b.p. vs alcohol
- Planar 120 school
Exam Example
- Exam pair:
- ethanal: aldehyde, CHO
- propanone: ketone, C=O in the chain
- both carbonyls; tests tell them apart
Common Misconceptions
- Do not confuse 1. NAMES with 2. BOND; state the difference before giving an example.
- Writing only “aldehyde CHO end” is not enough. Explain what it means in a complete sentence.
FBISE Exam Check
- Explain aldehydes and ketones, compare its two main parts, and include the correct chemical evidence.
- Structures. No solvent or perfume plant.
60-second revision
- Both have the carbonyl C=O.
- 1. NAMES: Methanal, ethanal, propanone, pentan-3-one.
- 2. BOND: C=O shorter/stronger than C-O, still polar.
- Exam reminder: Exam pair: ethanal: aldehyde, CHO propanone: ketone, C=O in the chain both carbonyls; tests tell them apart
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