atomic number
C1Academic/Scientific
Definition
Meaning
The number of protons in the nucleus of an atom, which determines its chemical properties and place in the periodic table.
An integer that uniquely identifies a chemical element. In neutral atoms, it also equals the number of electrons.
Linguistics
Semantic Notes
Refers to a fundamental property of an element, not a random identifier. In notation, often symbolized as 'Z'.
Dialectal Variation
British vs American Usage
Differences
No difference in meaning or usage. Both use the same term exclusively.
Connotations
Purely scientific, with no cultural or regional connotations.
Frequency
Equal frequency in academic and scientific contexts in both regions.
Vocabulary
Collocations
Grammar
Valency Patterns
The atomic number of [ELEMENT] is [NUMBER].[ELEMENT] has an atomic number of [NUMBER].Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “(no common idioms for this technical term)”
Usage
Context Usage
Business
Not used.
Academic
Used in chemistry, physics, and materials science textbooks and research.
Everyday
Rarely used outside of educational contexts.
Technical
Fundamental term in nuclear chemistry, spectroscopy, and periodic table discussions.
Examples
By Part of Speech
adjective
British English
- Atomic-number trends show periodicity.
- The atomic-number data is crucial.
American English
- Atomic-number trends show periodicity.
- The atomic-number data is crucial.
Examples
By CEFR Level
- (Not typically taught at this level)
- Hydrogen has the atomic number 1.
- The atomic number tells you how many protons are in an atom.
- Elements are arranged in the periodic table in order of increasing atomic number.
- The chemical properties of an element are largely determined by its atomic number.
- Isotopes of an element share the same atomic number but differ in their neutron count.
- The concept of atomic number resolved discrepancies in Mendeleev's early periodic table based on atomic weights.
Learning
Memory Aids
Mnemonic
Atomic Number = Proton Party in the nucleus. The 'Z' in 'Z number' can stand for 'Zentrale' (German for central), pointing to the central nucleus.
Conceptual Metaphor
An element's fingerprint or ID number.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with 'атомный вес' (atomic weight/mass). Ensure translation is 'атомный номер'.
Common Mistakes
- Confusing 'atomic number' with 'atomic mass' or 'mass number'. Using it as a countable item without 'the' (e.g., 'Hydrogen has atomic number 1' is less standard than 'Hydrogen has an atomic number of 1').
Practice
Quiz
What does the atomic number uniquely define?
FAQ
Frequently Asked Questions
Yes, it is always an integer because you cannot have a fraction of a proton.
No. By definition, each element has a unique atomic number.
Elements are listed in the periodic table in strict ascending order of their atomic number.
No. The atomic number (number of protons) defines the element and remains constant during ordinary chemical reactions. It only changes in nuclear reactions.