The structure of atoms developed throughout time since 410 BCE to now. “Leucippus of Miletus (ca. 435 BCE) and Democritus of Abdera (ca. 410 BCE) developed the atomic hypothesis.” Their Theory was that the world is made up of atoms moving around in empty space, also in continuous motion and constantly colliding into each other. The ancient Greek philosophers were the first people to have the theory of atoms and no one continued their theory until early 1803 which was where John Dalton modernised the ancient Greek idea.
John Dalton’s theory was proposed giving a lecture at the Royal Institutions in 1803. The theory stated that “All matter is composed of atoms, Atoms cannot be made or destroyed, All atoms of the same element are identical, Different elements have different types of atoms, Chemical reactions occur when atoms are rearranged, Compounds are formed from atoms of the constituent elements.” Dalton’s theory provided other scientists to continue on with Dalton’s theory, which lead them into new areas of experiments.
In the late 1800’s JJ Thompson, the Physicist discovered the sub atomic particle known as the electron. JJ Thompson made a model known as the “Plum Pudding” where you can see the pudding as positive charged and the plums as negatively charged electrons. This theory was invalid due to what is known as the Rutherford gold foil experiment, which is designed to probe an atom.
Rutherford’s gold foil experiment displayed that the atom is mostly empty space, the nucleus is positively charged and the nucleus carries most of the atoms mass. “This experiment involved the firing of radioactive particles through minutely thin metal foils (notably gold) and detecting them using screens coated with zinc sulfide (a scintillator).”
Neils Bohr in 1913 said when modelling the atom that electrons are in orbits around the nucleus various energy levels. For example, how the planets orbit around the sun.This led to possible calculations of possible energy levels for the orbitals. He also said that the emission of light occurs when an electron enters into an orbital which has lower energy levels.
References http://sciencenetlinks.com/lessons/history-atom-ancient-greeks/ http://www.rsc.org/chemsoc/timeline/pages/0450.html http://www.rsc.org/chemsoc/timeline/pages/1897.html http://www.universetoday.com/38326/plum-pudding-model/ http://www.rsc.org/chemsoc/timeline/pages/1911.html http://www.rsc.org/chemsoc/timeline/pages/1913.html http://www.rsc.org/chemsoc/timeline/pages/1926.html http://www.dummies.com/how-to/content/atomic-structure-the-bohr-model.html
References: http://sciencenetlinks.com/lessons/history-atom-ancient-greeks/ http://www.rsc.org/chemsoc/timeline/pages/0450.html http://www.rsc.org/chemsoc/timeline/pages/1897.html http://www.universetoday.com/38326/plum-pudding-model/ http://www.rsc.org/chemsoc/timeline/pages/1911.html http://www.rsc.org/chemsoc/timeline/pages/1913.html http://www.rsc.org/chemsoc/timeline/pages/1926.html http://www.dummies.com/how-to/content/atomic-structure-the-bohr-model.html
You May Also Find These Documents Helpful
-
In this experiment, you will have a chance to test the hypothesis that Ernest Rutherford used when determining the size of the nucleus. In his "gold foil experiment," Rutherford shot alpha particles at gold atoms. Once he realized that the alpha particles were hitting a concentrated positive mass, he developed the nuclear model of the atom. Next, he set out to determine the relative size of the nucleus compared to the rest of the atom. He reasoned that the smaller the nucleus, the less likely it was to be hit by an alpha particle. This led to a simple comparative ratio:…
- 744 Words
- 3 Pages
Good Essays -
A new atomic theory, in which all atoms of the same element are identical to one another and equal in mass, was proposed by the scientist Dalton. Although the theory had its flaws and was simple, it was revolutionary. Scientists became able to study the actual structure and mass of atoms after the discovery of radioactivity. Soon, isotopes were discovered, as atoms of the same element which have been built up to have different masses.…
- 1188 Words
- 5 Pages
Good Essays -
Different theories about the atomic structure were introduced over time. These theories changed as a result of development of different experiments. Leucippus was the first to introduce the theory of atomism, however he didn’t write about his theories in detail. However, Democritus, his student wrote about the theory of atoms in detail. He theorised that everything was composed of atoms and that atoms are solid and indestructible. He also had a theory that there’s a relation between the solidness of the material and the type of atoms it’s made of as atoms differ in shape, mass and size. For example: metal is made from solid atoms that interlock with each other mechanically to keep them in place. On the other hand water is composed of slippery smooth atoms that allow the water to have its flexible properties.…
- 1109 Words
- 5 Pages
Good Essays -
New hypothesis according to Dalton (1803): All matter is composed of tiny, indivisible, electrically neutral spheres called atoms. Atoms of the same element are all identical. Atoms of different elements have different masses.…
- 769 Words
- 4 Pages
Good Essays -
A new atomic theory, in which all atoms of the same element are identical to one another and equal in mass, was proposed by the scientist Dalton. Although the theory had its flaws and was simple, it was revolutionary. Scientists became able to study the actual structure and mass of atoms after the discovery of radioactivity. Soon, isotopes were discovered, as atoms of the same element which have been built up to have different masses.…
- 1323 Words
- 6 Pages
Powerful Essays -
The scientific definition of an atom has changed a lot throughout history. Currently, the atom is known as the basic unit of a chemical, but there was a time when that was not known among scientists. There were multiple scientists that contributed to the creation of the first Atomic Theory: Democritus, Antoine Lavoisier, Joseph Proust, and John Dalton. Dalton took the information that he had taken from the three scientists prior to him and put everything into one theory. The Atomic Theory is the most well-known and accurate theory we know right now. Later on in history, more scientists came to contribute to the understanding of the Atomic Structure. These scientists included: Sir J.J. Thomson, Robert Millikan, Ernest Rutherford, Niels Bohr,…
- 700 Words
- 3 Pages
Good Essays -
Six scientists were chosen to see which one had made the greatest contribution to our current understanding of the atom’s structure. Our knowledge of an atom’s appearance and structure have evolved from years and years of development and contribution from many different scientists. Scientist Ernest Rutherford had been the best contributor to the understanding of the atomic structure. Why Rutherford was chosen is because his work had information on protons, neutrons, and electrons, the main components that make up the atom, showed what the atom looks like when the three are put together, and had also been the discoverer of the nucleus which is the one of them most important parts of the atom’s structure.…
- 793 Words
- 4 Pages
Good Essays -
The modern atomic theory was developed by many scientists, such as Neil Bohr, Democritus, James Chadwick and John Dalton. Each of these intelligent scientists have found different discoveries in their research with the atom. Why has scientific understanding of the atom changed over time? This would be because each scientist has had a different approach and has discovered new understandings from their research. Without these men researching and experimenting, we would not know all of the different aspects of the atom.…
- 762 Words
- 4 Pages
Good Essays -
Quite a few scientists have helped to create and extend ideas on what an atom is and what its components are. One of these discoverers, John Dalton, developed the first modern atomic theory. Although much of his theory is still true today, one point was disproved by Ernest Rutherford.…
- 272 Words
- 2 Pages
Good Essays -
1. Explain how scientific observations led to the development of, and changes to, the periodic table.…
- 2160 Words
- 7 Pages
Good Essays -
In 1913, a Danish physicist named Niels Bohr put Rutherford's findings together with the observed spectra to come up with a new model of the atom in a real leap of intuition. I believe that the Bohr’s model of atom explains well about the atomic theory, because in his experiments it is shown and explained the structure of an atom. His famous suggestion is about that the electrons orbit around the nucleus of an atom. Bohr experimented with atomic spectrum that proved his suggestion.…
- 377 Words
- 2 Pages
Satisfactory Essays -
8. In 1897, J. J. Thomson made a discovery that proved the first part of Dalton’s atomic theory was correct. True…
- 466 Words
- 2 Pages
Satisfactory Essays -
Ernest Rutherford’s Gold Foil Experiment was a major stepping stone one the way to discovering what the atom was really made up of. From the beginning of his research with alpha particles to his discovery of the atomic nucleus, Rutherford made many contributions to the microscopic world of the atom. The Rutherford Experiment, otherwise known as the Gold Foil Experiment, was the crown of his achievements, and it was during this experiment that he discovered the atomic nucleus. (Aydin &Hanuscin, p.59) He made this happen by putting his past research on alpha particles to the test, such as the knowledge that an alpha particle should be less massive than the atom. Therefore the alpha particles should pass directly through the atom, unfazed. When the particles started to reflect off of the atoms in obtuse angles, Rutherford began to question the plum pudding model of the atom. It did not take him long to scientifically prove the model wrong, it only took about 2 years after the initial experiment to get enough proof to disprove the Plum Pudding Model and publish his own atomic model, The Rutherford Model. This article will be focusing on Rutherford’s Gold Foil experiment and how the experiment’s results changed how scientists would look at the structure of the atom for many years to come. (Nagendrappa, p.1013,1014)…
- 1497 Words
- 6 Pages
Powerful Essays -
The atom is the basic unit of matter and all life. The history of the study of the atomic nature of matter is the thinking process that goes on in the scientist’s heads. Further progress in the understanding of atoms did not occur until very famous scientist created the atomic theory. Here are some scientists who changed the way we learn about the atom, and the atomic nature of all life.…
- 1488 Words
- 6 Pages
Good Essays -
Neils Bohr came up with a observation that, since + and – charges electrons on the outside should come crashing into the nucleus cancelling both out. His experiment involved studying light coming from atoms that are ‘excited’ by electricity or flame. The light is made of distinct colour liens…
- 2172 Words
- 9 Pages
Better Essays