GCSE Physics (AQA)

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Pre-Electron Ideas

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Atomic structure Atoms and isotopes

Pre-Electron Ideas

2:13 History of the Atom
Spec 4.4.1.3
Previous Ions Next The Plum Pudding Model
  • Understanding of the atom has evolved over time.
  • In the 1800s, atoms were thought to be indivisible.
  • Around 1900, the electron was discovered, leading to the plum pudding model.
  • The plum pudding model depicted atoms as positive charges with electrons inside.
  • The shell model followed, with a nucleus at the center and electrons orbiting it.
  • Models have become more complex with more subatomic particles and irregular arrangements.
  • Models adapt to fit new scientific evidence.
  • Scientific models are based on available information and can disprove theories.
  • Exams require understanding the general order and progress of atomic models, not specific dates.
  • The concept of atoms was first proposed by Greek philosopher Democritus around 400 BC.
  • Democritus theorized matter was made of tiny, indivisible particles.
  • Particles were considered the smallest piece of matter, with empty space between them.
  • Non-contact forces between atoms are now known.
  • Dalton formalized these ideas in the early 1800s, but exam details are not required.

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