Observations and mathematical ideas are critical to the improvement of scientific models.
Discuss this statement with reference to scientific discoveries that have contributed to our understanding of the atom. (8 marks)
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If scientific models are not consistent with observations and mathematical ideas, then they need to be changed. The historical progression of models of the atom is an example of this scientific method in action.
→ The Geiger-Marsden experiment involved shooting a beam of alpha particles at a thin sheet of gold foil. It was observed that most alpha particles passed through the gold however some bounced back.
→ Rutherford explained these observations in his model. He postulated that a small, dense positively charged nucleus caused the alpha particles to bounce back and that this nucleus was surrounded by orbiting electrons. The atom was mostly empty space so the majority of alpha particles passed through.
→ This model was limited however as an electron orbiting the nucleus would be accelerating and would radiate electromagnetic radiation, losing energy and spiralling into the nucleus.
→ Bohr overcame this limitation and improved the atomic model by analysing observations of the hydrogen spectrum. He postulated that electrons occupied specific energy orbits and could jump from one energy level to another and electrons travelling from a higher to lower energy orbit would emit a photon, corresponding to emission lines on hydrogen’s spectrum.
→ Bohr developed a mathematical model explaining the specific wavelengths emitted which relies on Rydberg’s equation: `(1)/(lambda)=R((1)/(n_(f)^2)-(1)/(n_(i)^2))`.
→ This model was limited as it was only able to explain the hydrogen atom and wasn’t able to explain why electrons were quantised in such a way.
→ De Broglie built upon this model by postulating that electrons behaved as a wave. He stated that electrons behaved as standing waves with an integer number of wavelengths fitting the circumference of an orbit.
→ De Broglie’s contribution was critically supported by his mathematical model for calculating the associated wavelength `lambda=(h)/(mv)`
→ From these examples, it is clear that our understanding of the atom has been increased following observations and improved mathematical models.
Answers could also reference:
→ Thomson’s discovery of the electron.
→ Further contributions from Davisson-Germer as well as Schrodinger and Heisenberg.
If scientific models are not consistent with observations and mathematical ideas, then they need to be changed. The historical progression of models of the atom is an example of this scientific method in action.
→ The Geiger-Marsden experiment involved shooting a beam of alpha particles at a thin sheet of gold foil. It was observed that most alpha particles passed through the gold however some bounced back.
→ Rutherford explained these observations in his model. He postulated that a small, dense positively charged nucleus caused the alpha particles to bounce back and that this nucleus was surrounded by orbiting electrons. The atom was mostly empty space so the majority of alpha particles passed through.
→ This model was limited however as an electron orbiting the nucleus would be accelerating and would radiate electromagnetic radiation, losing energy and spiralling into the nucleus.
→ Bohr overcame this limitation and improved the atomic model by analysing observations of the hydrogen spectrum. He postulated that electrons occupied specific energy orbits and could jump from one energy level to another and electrons travelling from a higher to lower energy orbit would emit a photon, corresponding to emission lines on hydrogen’s spectrum.
→ Bohr developed a mathematical model explaining the specific wavelengths emitted which relies on Rydberg’s equation: `(1)/(lambda)=R((1)/(n_(f)^2)-(1)/(n_(i)^2))`.
→ This model was limited as it was only able to explain the hydrogen atom and wasn’t able to explain why electrons were quantised in such a way.
→ De Broglie built upon this model by postulating that electrons behaved as a wave. He stated that electrons behaved as standing waves with an integer number of wavelengths fitting the circumference of an orbit.
→ De Broglie’s contribution was critically supported by his mathematical model for calculating the associated wavelength `lambda=(h)/(mv)`
→ From these examples, it is clear that our understanding of the atom has been increased following observations and improved mathematical models.
Answers could also reference:
→ Thomson’s discovery of the electron.
→ Further contributions from Davisson-Germer as well as Schrodinger and Heisenberg.
