-
Dalton "Billard ball model"
Everything is composed of atoms, which are the indivisible building blocks of matter and cannot be destroyed.
J.J. Thomson studied cathode ray tubes and came up with the idea that the particles in the cathode beams must be negative because they were repelled by negatively charged items and attracted by positively charged items. He called these super tiny pieces of the atom, “electrons".J.J. Thompson discovered the electron, using the cathode ray tube experiment. -
Dalton "Billard ball model"
The model failed in almost everything. Being the first atomic model, it has different faults. One of them is the shape of the atom itself. The atom is not a sphere or is all full, but has different elements and is almost empty inside. Another thing that has not been established is the orbitals and the consideration of the electron and its movement throughout the atom. -
Thomson "Plum Pudding Model"
This theory was created by John Thomson in the lates 1890s, thanks to the experiments he did in the Crookes´ tube. When a voltage is applied across the electrodes, cathode rays are generated. He observed that these rays could be deflected by electric and magnetic fields. He discovered the electrons and discovered that atoms have a positive charge. However, the fault was that he didn´t know the location of electrons and if the atom had a nucleus or not. -
Thomson and the Crooks´ tube.
The Crooks´ Tube consists of a sealed glass container with two electrodes that are separated by a vacuum.
Through experimentation, Thomson observed that these rays could be deflected by electric and magnetic fields. He concluded that rather than being composed of light, they were made up of negatively charged particles he called “corpuscles”. -
Rutherford "Nuclear Atom"
The atom is conformed by two parts: the nucleus that is a tiny massive core composed by protons with positive charge, and the electrons with negative charge that are orbiting the nucleus. The experiment that he did to conclude this was the "Gold Foil Experiment", that consist in shooting a beam with alpha particles at a sheet of gold foil, and when he did this, a few particles were deflected because of the nucleus. -
Rutherford "Nuclear Atom"
The main contributions of this model were the small positive nucleus with the electrons moving around and that atoms are mostly empty space. This model is wrong because the presence of electrostatic attraction between the nucleus and the electrons. The electrons should fall into the nucleus, but they didn't. -
Bohr "Solar System Model"
This model was created by Niels Bohr in 1913. This theory says that electrons moved around the nucleus in only certain allowed circular orbits (energy levels). Bohr assigned a number, n, called a quantum number to each orbit or energy level. -
Bohr "Solar System Model"
This model failed because it did not provide a good model for atoms more complex than hydrogen and because the electrons have electrical charge and when they rotate around the nucleus they emit radiation and therefore they lose energy that would lead them to fall in the nucleus and this makes this model unstable for an atom. -
Schrödinger "Quantum Mechanical Electron Cloud"
This model was created by Erwin Schrödinger who stated that electrons do not move in set paths around the nucleus, but in waves. It is imposible to know the exact location of the electrons; instead, we have "clouds of probability" called orbitals, in which we are more likely to find an electron. -
Schrödinger "Quantum Mechanical Electron Cloud"
This model fails because it does not take into account the quantum number of the spin, it does not explain why an electron in a quantum state decays to a lower state if there is some free and it only explains the electronic structure of the atom and its interaction with the structure of other atoms.
