AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
The basic structure of an atom is a positively charged nucleus composed of…
Full specification wording
The structure of an atom: The basic structure of an atom is a positively charged nucleus composed of both protons and neutrons surrounded by negatively charged electrons.
An atom has a central nucleus containing protons, each with a relative charge of +1, and neutrons, which are uncharged.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 1 of 4
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
An atom has a central nucleus containing protons, each with a relative charge of +1, and neutrons, which are uncharged. Both have a relative mass of 1, so the nucleus carries the positive charge and nearly all the mass. Around it, at various distances, move the electrons, each with a relative charge of -1 and a mass roughly one two-thousandth of a proton's. A neutral atom holds exactly as many electrons as protons, so the charges cancel. A typical atomic radius is about 1 × 10⁻¹⁰ m. Charging an object never moves protons: only the loosely held outer electrons transfer, which is why an examiner awards nothing for an answer that speaks of transferring positive charge.
What earns the marks
- A positively charged nucleus containing protons and neutrons.
- Negatively charged electrons surrounding the nucleus.
- Relative charges of +1 for a proton, 0 for a neutron and -1 for an electron.
- An atomic radius of about 1 × 10⁻¹⁰ m.
Common mistakes and how to put them right
Placing the electrons inside the nucleus.
Giving the neutron a negative charge because of its name.
Explaining charging by the transfer of protons or positive charge, which scores zero.
Writing about positive electrons, which also scores zero.
Exam tips
- Learn the relative charges and masses of all three particles as a table; one-mark recall questions come up every year.
- In any electrostatics answer, transfer electrons and nothing else.
- Say surrounding or orbiting the nucleus rather than around the atom, which is ambiguous.
Try the lesson
The start of the The structure of an atom: The basic structure of an atom is a positively charged nucleus composed of both protons and neutrons surrounded by negatively charged electrons. lesson, made from checked teaching notes for this specification point.
Have a go first
Which statement describes the basic structure of an atom?
Listen
An atom has a central nucleus containing protons, each with a relative charge of +1, and neutrons, which are uncharged. Both have a relative mass of 1, so the nucleus carries the positive charge and nearly all the mass. Around it, at various distances, move the electrons, each with a relative charge of -1 and a mass roughly one two-thousandth of a proton's. A neutral atom holds exactly as many electrons as protons, so the charges cancel. A typical atomic radius is about 1 × 10⁻¹⁰ m. Charging an object never moves protons: only the loosely held outer electrons transfer, which is why an examiner awards nothing for an answer that speaks of transferring positive charge. A strong answer earns marks for these points. a positively charged nucleus containing protons and neutrons. negatively charged electrons surrounding the nucleus. relative charges of +1 for a proton, 0 for a neutron and -1 for an electron. an atomic radius of about 1 × 10⁻¹⁰ m. Exam tip: Learn the relative charges and masses of all three particles as a table; one-mark recall questions come up every year.
See it
Key words
Say what each word means before you turn the card.
nucleus
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protons and neutrons
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electrons
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neutral atoms
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See every definition
- nucleus
- The positively charged central part of an atom, composed of both protons and neutrons.
- protons and neutrons
- The particles that make up the nucleus, where protons have a relative charge of +1 and neutrons are uncharged.
- electrons
- Negatively charged particles that surround the nucleus, each with a relative charge of -1.
- neutral atoms
- Atoms that hold exactly as many electrons as protons, so the charges cancel.
Label the diagram
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1Box 1
2Box 2
3Box 3
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