Atomic structure
AQA GCSE Chemistry revision on Atomic structure. Aligned to the AQA GCSE Chemistry 8462 specification. This bank has 69 practice questions on this topic.
Sample questions (3 of 69)
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Question 1
Which subatomic particle has NO charge?
- A) Proton
- B) Electron
- C) Neutron
- D) Ion
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Answer: Neutron
Atoms have a tiny nucleus of protons (+) and neutrons (no charge), with electrons (-) orbiting around. The nucleus is ~10,000x smaller than the whole atom - most of an atom is empty space. Proton/neutron masses are both ~1 amu; electron mass is ~1/1836 (negligible).
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Question 2
The atomic number of an element equals the number of...
- A) Protons
- B) Neutrons
- C) Electrons in the outer shell
- D) Atoms in a molecule
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Answer: Protons
Atomic number defines the element - all carbon atoms have 6 protons; all iron atoms have 26. In a neutral atom, electrons = protons. Mass number = protons + neutrons. Isotopes of the same element have the same protons but different neutrons (e.g. carbon-12 and carbon-14 both have 6 protons; carbon-14 has 8 neutrons not 6).
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Question 3
An atom of sodium has 11 protons and 12 neutrons. Its mass number is...
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Answer: 23
Mass number is the total of protons + neutrons (the nucleons). Sodium-23 is the common isotope. Atomic number 11 tells you it's sodium; mass number 23 tells you the specific isotope. Sodium also has 11 electrons (neutral atom) arranged 2, 8, 1 in shells.
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