addition reaction
Low (C2/Technical)Formal, Technical, Academic
Definition
Meaning
A chemical reaction in which two or more molecules combine to form a larger single molecule, with no by-products.
In organic chemistry, a reaction where atoms or groups add across a double or triple bond, such as in alkenes or alkynes. This is a fundamental reaction mechanism forming new single bonds from pi-bonds.
Linguistics
Semantic Notes
Used almost exclusively in chemistry. The term 'addition' refers to the addition of atoms/groups to a substrate, not to mathematical addition. Contrasts with 'elimination reaction' and 'substitution reaction'.
Dialectal Variation
British vs American Usage
Differences
No significant differences in meaning or usage. Pronunciation differs slightly as per standard UK/US patterns for the constituent words.
Connotations
Purely technical with no cultural connotations.
Frequency
Identically low frequency in both varieties, confined to scientific/educational contexts.
Vocabulary
Collocations
Grammar
Valency Patterns
[Compound] + undergoes + addition reaction + with [reagent]The addition reaction + of [substrate] + with [reagent] + yields [product]Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “N/A”
Usage
Context Usage
Business
Not used.
Academic
Core terminology in chemistry textbooks, lectures, and research papers.
Everyday
Not used.
Technical
Fundamental concept in organic synthesis, chemical engineering, and materials science.
Examples
By Part of Speech
verb
British English
- The alkene will add bromine in an addition reaction.
- The catalyst causes the molecules to add across the double bond.
American English
- The alkene undergoes addition with hydrogen halides.
- We need to add the reagent slowly to favour the addition reaction.
adverb
British English
- The alkene reacted additionly with the electrophile (non-standard; 'underwent addition' is preferred).
- N/A
American English
- N/A
- N/A
adjective
British English
- The addition reaction mechanism is clearly electrophilic.
- We studied addition reaction kinetics.
American English
- The addition-reaction pathway was the most favourable.
- Identify the addition reaction product.
Examples
By CEFR Level
- This word is not used at A2 level.
- In chemistry, two things sometimes join together in an addition reaction.
- The addition of hydrogen to ethene is a classic example of an addition reaction, producing ethane.
- Unlike substitution, an addition reaction increases the number of atoms in the molecule.
- The regioselectivity of the electrophilic addition reaction is governed by Markovnikov's rule.
- We must consider whether the addition reaction proceeds via a syn or anti mechanism.
Learning
Memory Aids
Mnemonic
Think of an 'ADDition' reaction: you are ADDING parts (atoms/groups) directly onto a molecule, like adding decorations to a Christmas tree.
Conceptual Metaphor
A PIECE JOINING A PUZZLE. The double bond is an incomplete puzzle piece; the reagents are the missing piece that snaps into place, completing the structure.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with 'прибавление' (increase) or 'сложение' (mathematical addition). The correct conceptual translation is 'реакция присоединения'.
- The phrase 'addition reaction' is a fixed term; avoid translating 'reaction' separately as 'реакционная добавка' which is incorrect.
Common Mistakes
- Misspelling as 'addition reation' (missing 'c').
- Using 'additional reaction' (which implies an extra or supplementary reaction).
- Confusing with 'chain addition' polymerization, which is a specific subtype.
Practice
Quiz
What is the primary characteristic of an addition reaction?
FAQ
Frequently Asked Questions
No. Some polymerisation reactions (like chain-growth) are a series of addition reactions, but 'addition reaction' is a broader term for a single chemical event, not the process of making long chains.
No. By definition, a pure addition reaction has only one product—the adduct. If water is released, it is a condensation reaction.
The direct opposite is an elimination reaction, where a molecule splits into two (or more) smaller molecules.
Virtually never. It is a highly specialised term in chemical sciences.