According to Demokritos, the matter could be torn down and reduced to a final item. A final piece that can not be separated into smaller pieces. Democritus gave this basic element the name "atomos" meaning "indivisible". All kinds of matter in nature came from the combination of atoms and every object could be made with atoms.
Toward To Modern Atom
John Dalton was the first person to create a systematic model on the road to the concept of 'atom'. According to him, the union of the elements with each other at specific ratios pointed to the existence of particles which could not be divided. These "simple, fixed, exact numbers" between the elements were actually the proportion of the atoms. He was perfectly right in his mind and in this direction he developed the first atomic model in 1805
All matter consists of very small pieces called atoms. These atoms are indivisible, indivisible and indestructible.
All atoms of an element are the same in terms of features such as shape, mass, and volume. But it is different from the atoms of other elements.
Chemical reactions are the combination of the atoms of different elements. These atoms combine with each other in a simple way and at rates that can be expressed by integers.
Electrons By Thomson
Joseph John Thomson discovered the electron and this discovery surely hit Dalton's indivisible atoms. Thomson experimented with different materials. Since the result did not change regardless of the material used in the experiment, the atoms of each element should not be completely different from each other as Dalton argues. In every atom, the discovered electron must be able to find its own place, and electron should be abandoned with the idea of non-division of the atom because it could leave the atom and travel through the tube. On the other hand, the electron was a negatively charged particle, but the atoms were uncharged. So there must have been loads in the atom that would provide this charge balance. Another fixation was that the charge/mass ratio of the electrons was too high. This means that the electron is very small in mass. In the light of all this information, Thomson created a new atomic model. According to Thomson, the atom is composed of positive charges. There are negatively charged electrons buried in the atom.
The atom is composed of positively charged matter.
The electrons are buried in this positively charged matter and do not move.
The masses of electrons are so small that the entire mass of the atom is positively charged.
The atom is spherical.
Thomson's atomic model is also known as the plum pudding model, in which electrons are suspended and homogeneously distributed in the atom.
Rutherford Heads To The Wheel
Ernest Rutherford conducted a series of experiments and discovered the proton in the nucleus. What determines the structure of every element's atom was the number of positively charged particles it possesses in the nucleus. Since the atom was in neutral structure, it had to have as many electrons as the number of charged particles. Now Rutherford was ready to build his own atomic model, and by 1911 he had announced the nucleus atomic model.
Positive charges in the atom are collected in a very small volume called the nucleus.
Inside the atom there are as many electrons as positively charged particles, and these electrons travel in circular orbits around the nucleus.
The electrons are located quite far away from the nucleus and the atom is made up of a large space.
And Niels Bohr
Bohr created a new model in 1913 by combining Rutherford's atomic model and the idea that energy is quantized:
Electrons can be found in circular orbits with a specific energy, not a random circular orbit around the nucleus.
Electrons have the energy level of their energy level. The energy levels are expressed by integers such as n = 1, 2, 3, 4, 5, 6 or K, L, M, N, O, P, Q according to their proximity to the atomic nucleus.
An electron at a high energy level emits light in the form of photons when it reaches a lower energy level. If the opposite of this happens, it must receive energy from the outside in order to move to a higher energy level than it is. When an atom's electrons take energy from the outside and move to a higher energy level, this atom is called an "excited atom."
After all these discoveries, the studies of quantum physicists like Compton, Louis de Broglie, Wolfgang Pauli and Schrodinger have revealed the atomic model we know today. Now, with string theory, the atomic model is known as the most modernist form.
