John Dalton

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.

Democritus of Abdera was a greek philosopher born around 460 BC, a cheerful and blissful man. He was one of the two founding fathers of the Atomic Theory. His thought process on the theory, was that matter was comprised of tiny building particles called atoms. This theory was widely questionable at this time. As people were not very well accustomed with accepting new ideas, and/or new concepts of philosophy and science. This theory was only partially correct, and as scientist of the more modern age began to look deeper into Democritus’s work, they begin to make new theories and hypothesize new ideas about the atom. Which later on, would lead to the development of the atomic theory and the most accurate description of the atom with the work of Niels Bohr.

-Henry Gwyn Jeffreys Moseley- Worked with Ernest Rutherford, experimented with 38 metals, he found that the positive charge of each element’s nucleus increased by one from element to element as they were arranged in Mendeleev’s periodic table, lead to modern definition of atomic number (# of protons in atom’s nucleus) and the recognition the

  Then in 1661, Irish chemist Robert Boyle supported the philosophers’ theory of how chemical elements are made up of the simplest matter, backing the theory of how matter makes up all life and is the smallest living thing (Doc. 1). But a bombshell happened in 1803 when John Dalton backed up all three theories by discovering that atoms make up all matter, and chemical compounds are made of atoms (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

Democritus made the atomic theory widely known, which stated that the universe is composed of two elements: the atoms and the void in which these atoms exist and move. (More, 1646)

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

Over the course of the last 5000 years, mankind’s knowledge has been constantly advancing. Chemistry, a branch of science, has experienced a tremendous leap and expansions since ancient Greek civilization. One of the major breakthroughs in the advancement in Chemistry was the creation of the Atomic theory, which laid a foundation for the modern-day Chemistry and future of science. The Atomic theory introduced the idea of atoms, which are defined as the discrete units of matter. There are five key scientists that significantly contributed to the Atomic model over a span of thousands of years. They are: Democritus, John Dalton, J.J. Thompson, Ernest Rutherford, and Niels Bohr.

Stanislao Cannizzaro was born on July 13, 1826. When he was younger, he showed great skills in mathematics. He later became an assistant to Rafaelle Piria. Cannizzaro saw his dedication to his work that Piria influenced him to transform his study to chemistry. Cannizzaro later determined the different atomic weights. Dmitri Ivanovich Mendeleev always had a love for history, math, and physics. He attended the University of St. Petersburg where he formed the ideas of chemical compounds. Mendeleev found out that you could simplify the periodic table by separating them into different groups. He arranged them by the atomic weights and then later realized they had similar chemical properties. He had also given predictions of future elements and their properties.

- The discovery of neutrons solved the mystery why atomic mass and atomic number are different, since neutrons added mass to the atom but don’t add any

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 was an English chemist, meteorologist and physicist. He is known for making and finding work in the development of modern atomic theory. Dalton also made a huge advance in finding color blindness in people. In John's early life he was born into a Quaker family in England. Around 1790 John started to take up law and medicine in school but found his occupation and liking in chemistry. Dalton, born into a Quaker family, joined his 15 year old brother in running a Quaker school in Kendal. Dalton moved to Manchester to excel his work and became a private tutor for mathematics and natural philosophy.

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)