The Atomic Theory

For thousands of years Democritus’s Atomos theory was only believed to have been speculation, until the early 1800’s when an english chemist named John Dalton who used the theory of atomos or atoms to explain why elements always reacted in small ratios of whole numbers and how water absorbs different gasses for example that water absorbs carbon dioxide faster than nitrogen. From this Dalton claimed that:

Atoms of the same element can have different masses, this is called isotopes. After 200 years John Dalton discovery of the Dalton’s Atomic theory it is still used today John Dalton’s atomic theory is the foundation of which Chemistry was built on.

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

Thomson discovered the electron. He used a cathode ray tube (an electron gun) with a magnet and discovered that the green beam it emitted was made up of negatively charged particles. Thomson then determined that these negatively charged electrons needed something positive to balance them out. (Born, 2014)

Firstly, he believed that all matter was made of sphere-like atoms that were always in many different stages of motion. In addition, he theorized that atoms could not be destroyed, created, divided, or transformed into other atoms. Dalton based this assumption on the law of conservation of mass. Another theory of his was that elements were characterized by the weight of their atoms and that atoms of the same element had an identical weight. Finally, he believed that chemical reactions combined atoms into small whole-number ratios, and element reactions combine into more than one whole-number ratios. This theory was usually accepted due to the fact that it explained the laws of conservation of mass, as well as multiple and definite

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

A series of Cathode Ray experiments were held to study the effects of both magnetic and electric fields. These experiments determined the ratio of its charge to its mass. He concluded that they weren’t rays but that they were very light, very small negatively charged particles aka corpulse or more commonly known as electrons (Crash Course Video). Thomson also concluded that the mass of the charged particle was less than the mass of a Hydrogen atom. This proved that there was a particle smaller than an atom. Thomson tried to answer questions about the nature of atoms using a model, this model was called the Plum Pudding Model (Atomic Structure Prazi). This model depicted the atom as a spherical shape composed of uniformly distributed positively charged electrons

1913 – Henry Moseley tested whether elements should be based on the charge of the nucleus. He found that there was a pattern between adjacent elements. Moseley devised the basics of the atomic number.

The race for an answer is over! All the scientists out there, put down your beakers and eyedroppers for just a moment and educate yourselves through this article. A new discovery in chemistry has shaken the science world as we know it. Joseph John Thomson, an incredible scientist living amongst us today has discovered a new negative particle, one he has appropriately named the “electron”. Now we’re sure all of you are asking the same question: How did he do it? And of course, we have the answer! Thomson had discovered the electron during a series of experiments designed to “study the nature of electric discharge in a high-vacuum cathode-ray tube”. To put it simply, it had been had discovered by experimenting with beams of particles produced

Towards the end of the 19th century Joseph Thomson, discovered and experimented with cathode rays it was found that these rays had are constant negative charged particles, then later on they were called electrons by Thomson, the first subatomic particle he states that it would take about 2000 electrons to weigh the same as the lightest atom, Hydrogen

Thomson’s discovery of the electron in 1897 and the atomic model, with his findings of the atom containing electrons, each with an individual unit of negative charge. Thomson also found that electrons were very light when compared to the mass of the atoms in which they came from. This is because atoms were known to be electrically neutral, the remainder of the atom had to be positively charged and form most of the weight in the atom. Thomson used his plum pudding model of the atom to present this. How did thomson discover the atom? Thomson discovered the atom through his use of Crookes, or cathode ray, tube in his experiments. He showed that cathode rays were negatively charged, also he looked at positively charged

Thomson4 discovered the electron3 using a cathode ray4. In a cathode ray an electric current is passed through a discharge tube5 which causes a glowing light that, Thomson concluded, was made up of smaller particles. He then discovered that these particles had a negative charge and were actually electrons. Thomson knew that electrons had a negative charge and believed that matter must have a positive charge as well. From the knowledge he accumulated, he formed a model of what he believed the structure of the atom looked like. This model has come to be known as the Plum Pudding Model4. In 19004 a professor of theoretical physics, Max Planck4, discovered that when you vibrate atoms strong enough you can measure the energy. Planck called these packets of energy quanta. At the time, physicists believed that light consisted of waves. Albert Einstein4 concluded that the quanta behaved like discrete particles. For many years there was a controversy on whether light consisted of waves or particles. In 1911 Ernest Rutherford4 bombarded atoms with alpha rays. Rutherford used Radium as the alpha particles4 and shined them onto gold foil. This was called the Gold Foil Experiment4. The conclusion from this experiment was that positively charged matter scattered the alpha particles and that most of the space4 around these positively charged centers has nothing in it. Furthermore, Rutherford thought that electrons must exist somewhere within that empty space and that they orbited a positive center, like the planets orbit around the sun. Rutherford also speculated that atoms consisted of a compact positively charged nucleus4 as well as that most of the atom’s mass is contained in the nucleus. In 1919 Rutherford finally identified the particles of the nucleus as discrete positive charges of matter and named them protons4. He developed a model of the atom but, due to the theory of electricity and magnetism, it was predicted, according to this model,

Although difficult to imagine, there existed a point in time where people lived in an environment where everything was visually there, but what it was made up of remained a thoughtless mystery. Today, this is why atomic theory is an important basis for the foundation of chemistry, physics, and various other scientific discoveries. Without atomic theory, the basic building blocks of the world would remain unclear, which would make understanding the study of science almost impossible. Atomic theory explains the idea that within the composition of matter, there exists numerous particles called atoms. This idea of the atom has been experimented and researched by numerous scientists whom built upon each others discoveries-one scientist being J.J Thomson.

The Discovery of the Atom first came from the Greeks which made a theory “The idea that all matter is made up of tiny, indivisible particles, or atoms, is believed to have originated with the Greek philosopher Leucippus of Miletus and his student Democritus of Abdera in the 5th century B.C. (The word atom comes from the Greek word atomos, which means “indivisible.”)” (InfoPlease Atomic theory)