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Symbol
A nuclide is commonly represented using nuclear notation ᴬZX.
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Symbol
Recommended for Class 10
Symbol
A nuclide is commonly represented using nuclear notation:
ᴬZX
where:
`X` = chemical symbol `A` = mass number `Z` = atomic number
Atomic Number — Z
The atomic number equals the number of protons in the nucleus.
For a neutral atom, it also equals the number of electrons.
Mass Number — A
Mass number is the total number of:
protons + neutrons
Therefore:
**A = Z + N**
where `N` is neutron number.
So:
**N = A − Z**
Example
For:
²³₁₁Na
`A = 23`
`Z = 11`
Neutrons:
**N = 23 − 11 = 12**
Isotopes
Isotopes are atoms of the same element with:
same proton number `Z`; different neutron numbers; * therefore different mass numbers `A`.
Symbol — Advanced
Common Mistakes
Common Mistakes
- Mistake
Do not confuse mass number with atomic mass measured in atomic mass units.
- Mistake
`Z` is proton number.
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Practice
PQ
Q1. Identify A, Z and X in a nuclide symbol.
PQ
Q2. Calculate neutron number N.
PQ
Q3. Define isotope.
PQ
Q4. Calculate neutrons in ²³₁₁Na.
PQ
Q5. State the relationship A = Z + N.
Exam Practice
EQ
Q1. Explain nuclear notation ᴬZX.
EQ
Q2. Define atomic number and mass number.
EQ
Q3. Calculate neutron number.
EQ
Q4. Define isotopes.
EQ
Q5. Work a nuclide example.
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.