Edexcel GCSE Combined Science Physics 1SC0
Key Concepts of Physics
Motion and Forces
Conservation of Energy
Waves
Light and the Electromagnetic Spectrum
Radioactivity
Energy – Forces Doing Work
Forces and Their Effects
Electricity and Circuits
Magnetism and the Motor Effect
Electromagnetic Induction
Particle Model
Radioactivity
Isotopes, atomic number and mass number
- 3 things to know
- Paper 5
Overview
What atomic number and mass number count, finding neutrons by subtraction, reading nuclear symbols, what isotopes are, and why carbon-12 and carbon-14 react identically.
What you need to know
Answer each one before you reveal it.
What does the mass number of a nucleus tell you?
How is the number of neutrons in a nucleus worked out from its mass number and atomic number?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What does the atomic number of a nucleus tell you?
Model answer
The atomic number is the number of protons in the nucleus.
- 2
What does the mass number of a nucleus tell you?
Model answer
The mass number is the total number of protons and neutrons in the nucleus.
- 3
How is the number of neutrons in a nucleus worked out from its mass number and atomic number?
Model answer
Subtract the atomic number from the mass number.
- 4
In the symbol ¹³₆C, what do the numbers 13 and 6 represent?
Model answer
13 is the mass number and 6 is the atomic number.
- 5
How many neutrons are there in a nucleus of ¹³₆C?
Model answer
There are 7 neutrons, because 13 − 6 = 7.
- 6
What are isotopes?
Model answer
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
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