mass number
Let an agent explain mass number, compute neutron counts and isotope notation, and separate it from atomic number and atomic mass.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent explain mass number, compute neutron counts and isotope notation, and separate it from atomic number and atomic mass.
The total number of protons and neutrons in an atomic nucleus, denoted A, a dimensionless integer that distinguishes isotopes of the same element and is written as a superscript before the element symbol or after a hyphen, as in carbon-14; it differs from atomic number and from atomic mass.
What it is for: Describing nuclei and isotopes.
It can be compute neutrons from mass and atomic number; write isotope notation; explain differences from atomic mass; identify isotopes.
Distinguishing features
Integer count of nucleons
Dimensionless
Defines isotopes with atomic number
Distinct from atomic mass
What it looks like
Not physical; a number in notation.
How it is recognised
Superscript before element symbol
Hyphenated forms like uranium-235
Atomic mass is a non-integer average
Related models
is a kind of - category
is a kind of - category
is related to - related quantity
is related to - isotope abundance context
In practice
Families and kinds
mass numbers of stable isotopes
mass numbers of radioactive isotopes
mass numbers in nuclear reactions
Standards and regulation
IUPAC nomenclature for isotopes
Failure modes and hazards
Confusing mass number with atomic mass
Wrong neutron counts
Misplaced superscripts
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.mass-number
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Compute Nucleon counts.
Simple arithmetic.
Neutrons
Neutron number.
Neutrons
Neutron number.
- How many neutrons does this isotope have, given mass number and atomic number? measurement
- Which element is it? definition
Notation
Writing isotopes.
Notation
Notation.
- How is this isotope written in AZX and hyphen notation? definition
- Which convention does IUPAC recommend? provenance
Distinguish Related quantities.
Terms differ.
Mass
Atomic mass.
Mass
Atomic mass.
- How does mass number differ from atomic mass and relative atomic mass? definition
- Why is atomic mass not an integer? definition
Number
Atomic number.
Number
Atomic number.
- How does mass number differ from atomic number? definition
- Which defines the element? definition
Nuclear Reactions.
Mass number is conserved.
Conservation
Balancing equations.
Conservation
Conservation.
- How is mass number conserved in nuclear reactions and decay? definition
- What are the products of this decay? measurement
Stability
Isotope stability.
Stability
Stability.
- How does the neutron to proton ratio affect stability? definition
- Where is this isotope on the chart of nuclides? provenance
Teach Learning.
Common confusions.
Misconceptions
Errors.
Misconceptions
Misconceptions.
- Which misconceptions about mass number are common among students? provenance
- How can they be corrected? action
Examples
Worked examples.
Examples
Examples.
- What are worked examples for carbon, uranium and hydrogen isotopes? action
- Which exercises help? action
What the second pass must settle
- Should isotopes be separate entries?
- How should nuclide charts be linked?
- How should notation be rendered?