Structure of the Atom — Flashcards

Answer

The three fundamental sub-atomic particles are: 1. Electrons (e⁻) - negatively charged, negligible mass 2. Protons (p⁺) - positively charged, mass = 1 unit 3. Neutrons (n) - no charge, mass = 1 unit…

Answer

J.J. Thomson discovered the electron. He was awarded the Nobel Prize in Physics in 1906 for his work on the discovery of electrons.

Answer

Thomson's model (Christmas pudding model): - Atom consists of a positively charged sphere - Electrons are embedded in this positive sphere like currants in a pudding - Negative and positive charges ar…

Answer

Key observations: 1. Most α-particles passed straight through the gold foil 2. Some α-particles were deflected by small angles 3. Very few (1 in 12,000) α-particles rebounded (deflected by 180°) This…

Answer

Rutherford's conclusions: 1. Most of the atom is empty space 2. Positive charge occupies very little space 3. All positive charge and mass are concentrated in a tiny nucleus 4. Nucleus radius is 10⁵ t…

Answer

The major drawback was that revolving electrons should radiate energy continuously and spiral into the nucleus, making atoms unstable. However, atoms are actually stable, so this model could not expla…

Answer

Bohr's postulates: 1. Only certain special orbits (discrete orbits) are allowed for electrons 2. Electrons do not radiate energy while revolving in these discrete orbits 3. These orbits are called ene…

Answer

J. Chadwick discovered neutrons in 1932. Neutrons have no charge and mass nearly equal to protons. They are present in the nucleus of all atoms except hydrogen.