avogadro's constant
C1-C2 / ProfessionalAcademic / Scientific / Technical
Definition
Meaning
The fixed number of constituent particles (usually atoms or molecules) in one mole of a given substance.
A fundamental physical constant (6.02214076 × 10^23 mol^-1) used primarily in chemistry and physics to define the mole and to connect macroscopic measurements with atomic-scale quantities. It represents the exact number of elementary entities in one mole of a substance, which is now a fixed, defined value without uncertainty.
Linguistics
Semantic Notes
Named after the Italian scientist Amedeo Avogadro. It is a defined constant, not a measured one, since the 2019 redefinition of the SI base units. The term is used as a singular noun ('Avogadro's constant is...'). In older texts, it might be referred to as 'Avogadro's number'.
Dialectal Variation
British vs American Usage
Differences
No significant linguistic differences. Both varieties use 'Avogadro's constant' as the modern standard term. 'Avogadro's number' is an older, less precise synonym used in both varieties, but 'constant' is now technically correct. Spelling of 'Avogadro's' remains the same.
Connotations
Identical technical and academic connotations in both varieties.
Frequency
Extremely low frequency in general discourse. Identical high frequency within relevant scientific disciplines in both UK and US.
Vocabulary
Collocations
Grammar
Valency Patterns
[SUBJECT] has a value equal to Avogadro's constant.[VERB] the number of particles by Avogadro's constant.The amount, [NOUN], is related to Avogadro's constant.Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “NA (technical term not used idiomatically)”
Usage
Context Usage
Business
Virtually never used except in highly specialized chemical or materials science industries in technical reports.
Academic
Exclusively used in chemistry, physics, and materials science textbooks, lectures, and research papers. Core concept in stoichiometry and quantitative chemistry.
Everyday
Extremely rare. Might be mentioned in advanced secondary school or university study contexts.
Technical
The primary context. Used in laboratory manuals, scientific calculations, academic papers, and standards documents to relate mass to particle count.
Examples
By Part of Speech
verb
British English
- NA (not used as a verb)
American English
- NA (not used as a verb)
adverb
British English
- NA (not used as an adverb)
American English
- NA (not used as an adverb)
adjective
British English
- NA (not used attributively as an adjective)
American English
- NA (not used attributively as an adjective)
Examples
By CEFR Level
- NA (A2 level does not cover this term)
- NA (B1 level rarely covers this term)
- In chemistry class, we learned about Avogadro's constant and the mole.
- The value of Avogadro's constant is written on the periodic table in our lab.
- To find the number of atoms, multiply the amount in moles by Avogadro's constant.
- The 2019 redefinition of SI units fixed the exact value of Avogadro's constant, removing any measurement uncertainty.
Learning
Memory Aids
Mnemonic
Imagine a huge 'Avo'-cadro (a bowl of guacamole) containing exactly 602,214,076,000,000,000,000,000 (6.022x10^23) tiny pieces of tomato and onion, representing the particles in a mole.
Conceptual Metaphor
A BRIDGE or CONVERSION FACTOR (connecting the visible world of grams to the invisible world of atoms). A GIANT'S NUMBER (emphasizing its unimaginably large size).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- May be directly translated as 'постоянная Авогадро', which is correct. Avoid the calque 'число Авогадро' in formal modern contexts, though it is historically understood.
- Do not confuse with 'число Лошмидта' (Loschmidt constant), which refers to the number of molecules per unit volume of an ideal gas at STP.
Common Mistakes
- Pronouncing 'Avogadro' with a hard 'g' as in 'go' (it's a soft 'g' as in 'gem').
- Calling it 'Avocado's constant' (humorous malapropism).
- Treating it as a variable or approximate value (it is now an exact defined constant).
- Incorrect subject-verb agreement: 'Avogadro's constant are...' (should be 'is').
Practice
Quiz
What is the primary scientific field for the use of Avogadro's constant?
FAQ
Frequently Asked Questions
They refer to the same numerical value (6.02214076 × 10^23). Historically, it was called 'Avogadro's number' and was an experimentally measured quantity. Since 2019, it is a defined constant with an exact value and is formally termed 'Avogadro constant' or 'Avogadro's constant'.
It is large by design to create a practical bridge between the atomic scale and the human scale. One mole of a substance (like 12 grams of carbon-12) contains a macroscopic amount of material, but atoms are incredibly small, so it takes a vast number of them to make up a visible sample.
For most introductory purposes, using the approximation 6.02 × 10^23 is perfectly acceptable. The exact defined value (6.02214076 × 10^23) is used in high-precision scientific calculations and is the official SI value.
It is used as a conversion factor. For example: Number of atoms = (mass in grams / molar mass in g/mol) × Avogadro's constant. It links the mass of a sample to the number of elementary particles (atoms, molecules, ions) it contains.