Atomic History

Question 1

John dalton

Answer 1

• Discovered the atomic theory
• Atoms of a given element are unable to divide (Subatomic Particles)
• Atoms of a give element are identical (Isotopes)
• Atoms of a given element differ from other elements
• Atoms of a given element join into ratios and from compounds
• In chemical reactions, atoms of a given element cannot be created or destroyed, only rearranged.

Question 2

J.J Thompson

Answer 2

• Proposed the plum pudding model
• Concluded that atoms were spherical regions with positively and negatively charged particles within them.

Question 3

cathode tube ray

Answer 3

• Cathode tube ray allowed scientists to discover the nature of matter.
• Apply an electric field to the cathode tube ray allowed it to deflect towards a positive pole, proving that…
• cathode tube rays consists of negatively charged particles.
• negatively charged particles were found in all elements.
• particles have a high mass to charge ratio.

Question 4

Ernest rutherford

Answer 4

• Conducted the gold foil exp
• fired alpha particles into a thin sheet of gold.
• noticed that most particles passed through while some deflected, due to the repulsion of the positive nucleus.
• concluded that atoms were empty spaces with a positively charged dense nucleus at the centre.

Question 5

James chadwick

Answer 5

• Bombarded beryllium with alpha particles.
• Bombarding produce a highly penetrating stream of particles.
• Stream consisted of particles with the same size of protons however with no charge.

Question 6

Neil bohr

Answer 6

• Electrons move around the nucleus in fixed circular orbits.
• Electrons are based in their shells based on their energy levels.
• Electrons orbit without losing energy
• Electrons at ground state have the lowest amount of energy
• Electrons moving from a low to high energy level absorb energy corresponding to a specific wavelength.
• Electrons moving from a high to low energy level emit energy in photons, corresponding to a specific colour.