AQA GCSE Physics 8463
Atomic Structure
Electricity
Energy
Forces
Magnetism and Electromagnetism
Particle Model of Matter
Space Physics
Waves
Atomic Structure
Mass number, atomic number and isotopes
- 3 things to know
- Paper 1
Overview
Why an atom has equal numbers of electrons and protons and no overall charge, atomic number and mass number, working out the number of neutrons, reading the two numbers written before a chemical symbol, isotopes and how they differ, and how an atom becomes a positive ion by losing an outer electron.
What you need to know
Answer each one before you reveal it.
How is the number of neutrons in an atom worked out?
When a nucleus is written with two numbers before its chemical symbol, which one is written above the other?
Questions from this subtopic
Each one with the model answer underneath.
- 1
How does the number of electrons in an atom compare with the number of protons in its nucleus?
Model answer
The two numbers are equal.
- 2
Explain why an atom has no overall electrical charge.
Model answer
It contains equal numbers of protons and electrons, so the positive and negative charges cancel out.
- 3
What is meant by the atomic number of an element?
Model answer
It is the number of protons in the nucleus of an atom of that element.
- 4
What do all atoms of a particular element have in common?
Model answer
They all contain the same number of protons.
- 5
What is meant by the mass number of an atom?
Model answer
It is the total number of protons and neutrons in the nucleus.
- 6
How is the number of neutrons in an atom worked out?
Model answer
Subtract the atomic number from the mass number.
Other ways to work this
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