Atomic Theory - Essay

It was a great day in May of 1932 and when we finally received answers to the other particle in the nucleus. After many years of questions and theories; one man James Chadwick has discovered a new uncharged particle, the neutron. Chadwick had been studying to find this particle since 1914 in Germany with Hans Geiger, unfortunately due to World War I he was arrested and his studies were put on halt. Although he was in prison he was still able to do some scientific studies after creating a science club with some fellow prisoners; and convincing the guards to allow them to have a lab. Eventually he was released and return to England where he earned his PhD at Cambridge with Ernest Rutherford.

John Dalton wrote the modern atomic theory, a fundamental component of that is, the mole ratios of elements in a compound will be small whole numbers.

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:

The pioneering work of Becquerel in 1896 (the discovery of uranium), and the Curies (who subsequently discovered radium and polonium and the energy and heat given off by these new elements which they called radioactivity) led to the remarkable work of Ernest Rutherford. He was a physicist, whose experiments showed that some heavier elements spontaneously changed or decayed into lighter elements (unstable 'parent' elements giving off protons and neutrons to form a 'daughter' element) through the process of radioactivity. He discovered that radioactive materials decay at a very predictable rate, and that lead was the final decay product of uranium. Using Rutherford's ideas, Bertram Boltwood pioneered a method of radiometric dating in 1907. He hypothesized that since he knew how long it takes uranium to break down, he could measure the proportions of lead in uranium ores, and use his calculations to date how long those ores had existed,

By firing massively charged particles at an atom, he found that atoms are made up of smaller particles (Doc. 1).  This would lead to his discovery of protons also known as alpha particles (OI). After that, he bombarded gold foil and observed that some of the atoms passed through the foil. Therefore, he concluded that atoms are composed of empty space (OI).  

John Dalton was a British chemist born in 1766 in England to a Quaker family. His family was poor and he was homeschooled until at age 15. He and his brother ran a school. He had the biggest effect on the atom. He was the first to bring back the idea of an atom and prove it. One reason Dalton’s discovery is important is without it

Around 2,500 years ago, Democritus and his partner Leucippus were the first ones to develop the atomic theory in written history. Their theory proposed that every kind of matter was made up of tiny particles, which were named atomos, which means that it is indivisible. This meant that Democritus and Leucippus thought there were little particles of everything, but, the next breakthrough in atomic theory wasn’t made until the early 1800s with a french chemist by the name of Antoine Lavoisier, he was the one who came up with the idea of the law of the conservation of mass, which states that matter stays the same even when it changes shape or form. Then, James Dalton said that all matter was made up of atoms, which were indivisible, and unbreakable.

The second main contributor toward the atomic structure was John Dalton. John Dalton was the one who brought the atomic theory talk back into play after 2000 years from Democritus. Dalton become fond of the atomic structure following his love from meteorology. He claimed that the forces of repulsion that caused pressure only were between the same atoms and the atoms inside a mixture had different weights and complexity. He then decided to calculate the atomic weights by determining the percentages of each composition in a compound. This allowed him to be able to

Rutherford’s understanding of the atom was that the protons were clustered together in the nucleus. The nucleus is then surrounded by empty space occupied by electrons. (Lucas & Wright, 2001)

Around 1803 John Dalton, an English chemist developed the first useful atomic theory of matter. Amedeo Avogadro, the Italian chemist in 1811 published an article drawing the distinction between the atom and the molecule, which now is known as “Avogadro’s

Also while he was there, he was invited by Professor J.J Thomason to study the conductivity of gases, resulting in a paper about dividing atoms and molecules into ions. This lead Rutherford on to taking a closer look at ion-producing radiations and he discovered that putting uranium near foil will result in one type of radiation being easily soaked up or blocked, while another type had no problem penetrating the same foil. Then, he labeled the two radiation types “alpha” and “beta.” He then found out that the alpha particle was the same as the nucleus of the helium atom, and the beta was the same as an electron or composition. He took a professorship at McGill University of Montreal and left Cambridge in 1902. In 1903, he and Fredrick Soddy introduced their disintegration theory of radioactivity, and it claimed that radioactive energy was emitted from within an atom and that when alpha and beta particles were emitted at the same time they caused a chemical change across elements. Rutherford and Bertam Borden Boltwood, continued to categorize radioactive elements into what they called a “decay series.” Rutherford was honored with discovering the radioactive gas radon while at McGill. He achieved fame for his contributions to understanding of radioelements, and published many magazine

Before Rutherford’s Geiger-Marsden experiment the most popular model of the atom was the “plum pudding model” developed in 1904 by the person who also discovered the electron in 1897, J.J. Thompson. It was the most common model of the atom and stated that electrons (plum) floated around with

John Dalton, a British chemist and physicist, that was born on the 6th of September 1766. His study of gases led Dalton to wonder about what these invisible substances

Curie thus began studying uranium radiation and made it her doctoral thesis. With the aid of an electrometer built by Pierre, Marie measured the strength of the radiation emitted form uranium compounds and found it proportional to the uranium content, constant over a long period of time and influenced by external conditions. She detected a similar immutable radiation in the compounds of thorium. While checking these results, she made the discovery that uranium pitchblende and the mineral chalcolite emitted four times as much radiation as their uranium content. She realized that unknown elements, even more radioactive then uranium must be present.

This is what led Curie to take Becquerel’s work a few steps further and conduct her own experiments on uranium rays. She discovered that the rays were constant no matter what form or condition of the uranium. She theorized the rays came from the atomic structure. This idea was revolutionary and created its own field in science, known as the atomic physics, this is when Marie coined the word “radioactivity” to describe the phenomena. Even when they had their first daughter Irene in 1897 there work did not slow. Pierre then stopped his own studies to help Marie with her new discovery of radioactivity. In 1898 they discovered a new radioactive element. They named it polonium after Marie’s native country, Poland. They detected the presence of another radioactive element and called this radium. In 1902 they had extracted pure radium to prove its existence as a unique chemical element.