electron affinity
C2Formal, Technical, Academic
Definition
Meaning
A measure of the energy change when an atom in its gaseous state gains an electron to form a negative ion.
In chemistry and physics, it quantifies the likelihood or ease with which a neutral atom accepts an electron, typically expressed as a negative value for exothermic processes. Conceptually, it indicates an element's 'desire' for an additional electron.
Linguistics
Semantic Notes
Despite 'affinity' suggesting attraction, the thermodynamic sign convention means a more negative value indicates a greater release of energy and thus a stronger 'affinity' for the electron.
Dialectal Variation
British vs American Usage
Differences
No significant lexical differences. Spelling of related terms follows regional conventions (e.g., 'ionisation' vs. 'ionization').
Connotations
Identical technical connotations in scientific contexts.
Frequency
Exclusively used in scientific discourse with equal frequency in both varieties.
Vocabulary
Collocations
Grammar
Valency Patterns
The electron affinity of [Element] is...[Element] has a high/low electron affinity.Electron affinity increases/decreases across...A negative electron affinity indicates...Vocabulary
Synonyms
Neutral
Weak
Vocabulary
Antonyms
Usage
Context Usage
Business
Not used.
Academic
Core concept in undergraduate chemistry and physics courses, particularly in discussions of periodic trends, chemical bonding, and thermodynamics.
Everyday
Not used.
Technical
Essential in research papers, material science, computational chemistry, and spectroscopy for predicting compound stability and reactivity.
Examples
By Part of Speech
verb
British English
- The atom will readily electron-affinise under those conditions. (Note: 'electron-affinise' is a rare, non-standard formation)
American English
- The process electron-affinizes the species. (Note: 'electron-affinizes' is a rare, non-standard formation)
adjective
British English
- The electron-affinity measurements were crucial. (hyphenated attributive use)
American English
- We studied the electron affinity trends. (noun used attributively)
Examples
By CEFR Level
- Chlorine has a high electron affinity, which makes it very reactive.
- Scientists can measure the electron affinity of different elements.
- The exceptionally high electron affinity of fluorine underpins its role as a powerful oxidizing agent.
- Theoretical models predicted the element's positive electron affinity, contradicting earlier experimental data.
Learning
Memory Aids
Mnemonic
Think of 'affinity' as an atom's 'friendship' for an extra electron. A strong friendship (high affinity) means energy is released (a happy, stable outcome) when they meet.
Conceptual Metaphor
ATOMS ARE ECONOMIC AGENTS: An atom with high electron affinity is a savvy investor, readily accepting (gaining) an electron because the transaction releases energy (profit).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Direct translation 'электронное сродство' is correct but may sound abstract. The concept is identical.
- Beware of confusing with 'electronegativity' ('электроотрицательность'), which is a related but distinct property of bonded atoms.
- The sign convention (negative = energy release) can be counter-intuitive.
Common Mistakes
- Confusing 'electron affinity' with 'electronegativity'.
- Forgetting that a more negative value means a greater affinity.
- Using 'electron affinity' to describe the loss of an electron.
- Misstating periodic trends (e.g., Noble gases have very low affinity, not high).
Practice
Quiz
Which statement about electron affinity is correct?
FAQ
Frequently Asked Questions
A more negative electron affinity value (e.g., -349 kJ/mol vs. -200 kJ/mol) indicates a greater release of energy and thus a stronger tendency to accept an electron.
Electron affinity is a measurable thermodynamic quantity for an isolated atom gaining an electron. Electronegativity is a dimensionless, relative scale estimating an atom's ability to attract shared electrons in a chemical bond.
Yes. A positive electron affinity means energy must be added for the atom to accept an electron, indicating the resulting anion is less stable than the neutral atom (e.g., as seen in noble gases like Neon).
For oxygen, adding an electron to the small 2p subshell causes significant electron-electron repulsion, offsetting the energy gain from nuclear attraction. Sulphur's larger 3p subshell mitigates this repulsion, leading to a more negative (more exothermic) first electron affinity.