Atomic StructureEdexcel GCSE Physics: Flashcards

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Describe the basic structure of an atom.

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Describe the basic structure of an atom.: A small, positively charged nucleus (protons and neutrons) surrounded by negatively charged electrons orbiting it.
What is the approximate diameter of an atom?: Of the order of 10⁻¹⁰ m.
What is the atomic (proton) number?: The number of protons in the nucleus of an atom.
What is the mass (nucleon) number?: The total number of protons and neutrons in the nucleus.
Define isotope.: An atom of the same element with the same number of protons but a different number of neutrons.
State the relative charge of a proton, neutron and electron.: Proton +1, neutron 0, electron −1.
What is a positron?: A particle with the same mass as an electron but a positive charge.
Why is a neutral atom overall uncharged?: Because it has equal numbers of protons and electrons, so the charges balance.
When do electrons change orbit?: When the atom absorbs or emits electromagnetic radiation.
How does an atom form a positive ion?: By losing one or more outer electrons.
Describe the plum pudding model of the atom.: A ball of positive charge with negative electrons embedded throughout it.
What did Rutherford's alpha scattering experiment show?: That atoms have a tiny, dense, positively charged nucleus, with most of the atom being empty space.
What did the Bohr model propose about electrons?: That electrons orbit the nucleus at specific, fixed distances (energy levels).
What evidence from Rutherford's experiment showed the nucleus is positively charged?: Some alpha particles (positive) were deflected or bounced straight back, showing repulsion from a concentrated positive charge.