Scientists have changed the model of the atom as they have gathered new evidence. One of the atomic models is shown below.
A large black cross in a purple circle with a black line around the purple, with 10 small green balls dispersed within the purple circle.
What experimental evidence led to the development of this atomic model from the one before it?
A few of the positive particles aimed at a gold foil seemed to bounce back.
The colors of light emitted from heated atoms had very specific energies.
Equations were used to identify regions around the nucleus where electrons would likely be.
Cathode rays were bent in the same way whenever a magnet was brought near them.
The experimental evidence that led to the development of this atomic model is:
- A few of the positive particles aimed at a gold foil seemed to bounce back: This observation indicated that there must be a concentrated positive charge in the center of the atom, which became known as the nucleus. This contradicted the previous model, which suggested that the positive charge was evenly distributed throughout the atom.
- The colors of light emitted from heated atoms had very specific energies: This observation led to the understanding that electrons occupy specific energy levels within an atom. When an electron transitions from a higher energy level to a lower one, it emits light of a specific energy corresponding to the energy difference between the levels. This supported the idea of electrons having specific regions or orbits around the nucleus.
- Equations were used to identify regions around the nucleus where electrons would likely be: Through mathematical calculations and equations, scientists were able to determine the probability of finding an electron in a specific region around the nucleus. This helped develop the idea of electron orbitals, which represent the regions where electrons are most likely to be found.
- Cathode rays were bent in the same way whenever a magnet was brought near them: This observation indicated that cathode rays were composed of negatively charged particles. These particles were identified as electrons and their behavior suggested that they were particles with mass and charge. This supported the idea of electrons being separate particles within the atom rather than a distribution of positive charge throughout.