The development of the theories into the structure of an atom

Over time many theories have been developed into the structure of the atom and what the world around us is composed of. Many scientists and philosophers have dedicated their life works into trying to understand how atoms work and what they are made up of, although not all theories have been accepted they have all come together to form what we know today.
It all started from a Greek scientist called Democritus, who developed the idea that everything is made up of smaller things, which he named atomos. Due to his revelation in science many people consider him to be the 'Father of modern science', although his work wasn't solely basedon science he was able to use the work of philosophers such as Leucippus and Anaxagoras. Democritus also believed that between atoms there was nothing but empty space, that they are indestructible and they are always in motion. Democritus also believed that there wasn't just one type of 'atomos' and they differ in size and shape. The fact that Democritus made his discovery in 400's BC shows that he was ahead of his time and due to his work it lead to the development in modern day science, hence being referred to as the 'Father of modern science'.
Not long after the discoveries of Democritus a very famous philosopher; Aristotle made his opinions known that he believed there was no such thing as atoms and that everything is simply composed of the four elements; earth, fire, air and water. This was a new beginning for the atomic theory, although not a good one, creating what could be called a 'dark age' for science. As Aristotle taught what he thought to many people it lead to the discoveries of Democritus being overlooked for over 2000 years. Due to the work of Aristotle he dramatically slowed down the evolution of the atomic theory, mainly because he was a philosopher and not a scientist.
Later Robert Boyle used physical experiments(studied gases) in order to prove his theories, unlike Democritus and Aristotle. Robert Boyle is sometimes referred to as the 'Father of Chemistry' due to the amount of work he put into his experiments and his extensive work on materials. Firstly Boyle was able to distinguish the difference between a mixture and a compound, the use of physical experiments by Boyle created a lot of controversy and due to this his work was largely impeded by the church. Although due to the experiments performed by Boyle it meant there was now physical evidence backing up theories, also his work could also be published. Boyle was most famous for Boyle's law, which he proved with his experiments, it stated that when a gases volume is decreased the pressure created increases and is proportional, he said that this was due to the gases being made up of tiny particles, or corpuscles as he named them. Due to his discovery he tried to construct and 'corpuscular theory' and also he defined what an element is, but also contributed to many modern forms of chemistry which is used everyday; such as the litmus test.
The use of physical experiments continued with the work of Isaac Newton in 1704, who like Robert Boyle studied gases and his work was also heavily impeded by the church. The main aim of his experiments was to find evidence that atoms actually existed and therefore see whether previous hypotheses and predictions developed by other scientists were accurate and true to life. In his experiments he found that atoms do in fact exist and they make up everything around us, although he began to understand that atoms are in fact moving constantly and are not stationary. This helped him when he explained that there are little pieces of mass swimming everywhere, he also proposed a mechanical universe where small, solid masses were in motion. Newton is well known for his work in science, namely physics, but with his contribution to chemistry he was able to help explain how the world around us works and therefore make the picture into atomic theory clearer.
The very next important development in atomic theory was discovered in 1827 by Robert Brown, who was a Scottish botanist. He discovered Brownian motion, which was the random movement of particles in a fluid, resulting in collisions. He made this very important detection when looking at pollen grains in water under a microscope, he found that the particles released from the grains moved randomly, for no apparent reason and he couldn't explain why they did this, but at a later date Albert Einstein was able to explain why Brownian motion took place(the particles being pushed around by the molecules in the water).
Later a theory was developed through the work done by other scientists and philosophers, this was created by John Dalton, who was an English Chemist, so the theory was named Dalton's theory. This theory stated that firstly matter is composed of extremely small particles called atoms, secondly that atoms are indivisible and indestructible, thirdly that atoms of a given element are identical in size, mass and chemical properties and that atoms of specific elements are different than those of other elements. The final conclusion in the theory is that in a chemical reaction, atoms separate, combine and/or rearrange. This theory developed by Dalton allows many reactions and phenomena to be explained. This theory wouldn't have been created without the hard work and the intelligence of many other brilliant scientists.
The next very large discovery comes with the work of scientist JJ. Thompson in 1904, although his work in the atomic theory may not have been accurate he still made a large contribution and his work lead to many large improvements in atomic theory. Thompson developed a model into the structure of the atom, which is commonly known as the plum pudding model or the blueberry muffin model, again the use of experiments helped him to create the model, he did this by creating a cathode ray, this was a tube that when a high voltage current is passed through it and atoms hit the outside of it it glows. When he placed a magnet close to the cathode ray it allowed him to see what happened to the atoms, when conducting the experiment he found that most of the particles were negative or beta particles. This allowed him to come up with the theory that an atom is made up of a sphere of positive charge, with negative electrons inside it, i.e. it looked like a plum pudding. But as we know today the plum pudding model was incorrect and it took Ernest Rutherford and his team to prove that and replace the plum pudding model with the nuclear model of an atom.
In 1908/1909 Ernest Rutherford and his team discovered that the plum pudding model was incorrect and were able to replace the model with a correct representation of a atom. His discovery was again found during an experiment, he was firing alpha particles at a very thin piece of foil, there were sensors set up all around the foil, so the path of the alpha particles could be tracked. At first thought they predicted that the particles would pass straight through the foil, however in the findings of the experiment they saw that a very small amount of atoms were deflected to the side and back towards the atom stream. Due to the results of the investigation it led Rutherford to conclude that the mass of an atom is directly in the centre(nucleus) and that most of an atom is made up of empty space. This allowed him to develop the nuclear model into an atom, which showed that the interior of an atom was beginning to be understood and we could now find out about the charge of an atom, thanks to Ernest Rutherford.
An English physicist called Henry Moseley had previously worked with Ernest Rutherford and several years later in 1913 he made many contributions to chemistry that made a large impact on modern chemistry today. Before Moseley had an influence the periodic table was known as a sequence of elements based on their atomic masses. Due to the fact that elements were placed in order, depending on their atomic mass it left many gaps where some elements hadn't been discovered, Moseley stated this and said that the order of masses was blindly used and did not take into account the elements physical properties. Also he developed Moseley's law, which uses the X-ray spectra of various chemical elements that were found in the diffraction of crystals, by using this he found a direct link between the length of the wavelength produced and the atomic number of the element. Due to this he suggested that instead of relying on the atomic mass of an element we should instead use the physics of the element to figure out their logical order on the periodic table, this made it easier to figure out the missing elements.
Later a Danish Physicist, by the name of Neils Bohr (1922) suggested that within an atom electrons don't just spiral into the nucleus, but instead they orbit in different levels, which are sometimes called energy levels or shells, this was referred to as Bohr's model of the atom. His model created a sensible view of the interior of an atom, as it also seemed far more logical than others before him. He also suggested by looking at the number of electrons an atoms has you can determine the physical properties that the element would have and this made it easier to separate the atoms and distinguish between each one. The work done by Bohr helps us to understand why certain atoms bond with others and why some stay the same, as it is all to do with the number of electron they posses and this dictates their reactivity. Due to Bohr's brilliant work in physics and his discovery of energy levels this led to him winning the Nobel prize in physics in 1922.
Very few years later in 1924 a French physicist called Louis de Broglie suggested that electrons are like light and could act as both particles and waves. He proved his hypothesis later with experiments, showing that electrons can be bent or diffracted when passing/travelling through air, similarly to light. This led De Broglie to develop the theory that in an atom an electron moves very much like light, so he created his own adaptation of Bohr's model of an atom, but instead of the electrons just orbiting the nucleus in their energy levels the waves produced by the electron when orbiting the nucleus created a standing wave, also giving a specific wavelength, energy and frequency.
Just under 20 years before Louis de Brogile made his contribution to the atomic theory the brilliant and largerly known Albert Einstein used mathematics and physics in order to prove and better Brownian motion. Due to the amazing mind of Albert Einstein he is sometimes referred to as “ The Father of Modern Physics” and he also won the Nobel prize, but also because of his work into atomic theory scientists were able to build upon that and go on to win the Nobel prize themselves. Albert Einstein was also interested in proving the exsistance of atoms and he did this mathematically, but he didn't stop there, he used the Brownian motion developed by Robert Brown in 1827 and the fact that the molecules in a liquid push around any other particles to explain what happens to both the invisible molecules and the visible particles during this motion, although these molecules cannot be seen the chaotic movement of the immersed particles suggests that they are present. Einstein suggested that the movement of these particles could produce statistical fluctuations, as the molecules pushed them in one direction and then another, this showed us that even though these molecules are invisible the pattern created by their movement creates a zig-zag, he observed this in 1905. This meant that he later deduced that although the visible particles are much larger they still generate pressure in the same way as the invisible molecules, in which they were immersed. If the concentration of the larger, visible particles varies they start to move and flow throughout the invisible molecules in order to even out their concentration. By using what he discovered Einstein was able to create a calculation in order to accurately calculate the average distance an immersed particle would travel in a given time. His calculations could easily be tested by observing the visible motion of particles in a fluid under a microscope, using a stopwatch.
Another Nobel prize winning scientist named Wolfgang Pauli, who was an Austrian theoretical physicist won the Nobel prize in physics in 1945, despite making his break though discovery into atomic theory in 1925. In 1925 Pauli was able to use mathematics in order to explain the behaviour of electrons within atoms, the rule that he used to explain the behaviour of these electrons is called “the Pauli exclusion principle”. This rule states that no two electrons within an atom can possess the same quantum numbers, these quantum numbers define the energy of the electron, in terms of it's orbiting distance from the nucleus, the orbits shape, the orientation of the axis of the orbit and the electrons spin in it's own axis. This all helps to explain why electrons behave the way they do, but Pauli didn't stop there, he also was the first to suggest the exsistance of subatomic particles and he also could fully understand the theory of general relativity, this proves that he had a very high level of intelligence. In terms of his suggestion of subatomic particles he said that they have no charge and very little mass but also that they can travel at a speed close to that of light. The work that Pauli did and the principle that he created is actually considered one of the fundamental laws of physics and he enabled many scientists after him to have a clear view of the behaviour of electrons of each and every known chemical element.
Another scientist who created a principle of science is Werner Heisenberg, he was a German physicist and even worked with Neils Bohr, Heisenberg made many discoveries in science, but one of his main ones was the “Uncertainty Principle”. From this principle he suggested that although electrons are in orbit of the nucleus they don't actually travel in neat orbits. By using mathematics Heisenberg was able to calculate the behaviour of electrons and subatomic particles, the discovery of this calculation helped create a clear view of the modern atom because scientist can now compare the number of electrons an atom possesses. Heisenberg was able to link mathematics into this field of science and due to this he made very large developments, which were detrimental to the development of the understanding of the structure of an atom.
To conclude the development of theories describing the structure of the atom have evolved immensely over the course of many years due to the dedicated work of many scientists and philosophers. Although some of them, such as Aristotle may have been incorrect in their theories they have still helped to reveal the cloudy world which is the atom and without them we wouldn't have developed in science the way we have today, it is all thanks to them.