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300
Democritus
300BC
Atom the indivisible particle
Atomos (in ancient Greek) means "that which cannot be further broken down into smaller pieces".
Talks about the atom as the smallest particle of matter.
Defines the atom as an indivisible particle
Explains certain natural occurrences such as the existence of elements
Does not give a scientific view of the atom only a conceptual definition
Does not talk about subatomic particles
(Electrons, Protons, Neutrons) -
Antoine Lavoisier
Widely credited as the “father of modern chemistry”, Antoine Lavoisier was a French chemist and a central figure in the 18th-century chemical revolution. He formulated a theory of the chemical reactivity of oxygen and co-wrote the modern system for the nomenclature of chemical substances. -
Law of conversation of mass
Established in 1789 by French Chemist Antoine Lavoisier
States that mass is neither created nor destroyed in any ordinary chemical reaction.
Or more simply, the mass of substances produced (products) by a chemical reaction is always equal to the mass of the reacting substances (reactants). -
John Dalton
ohn Dalton was born September 6, 1766, in Eaglesfield, England. During his early career, he identified the hereditary nature of red-green color blindness. In 1803 he revealed the concept of Dalton’s Law of Partial Pressures. Also in the 1800s, he was the first scientist to explain the behavior of atoms in terms of the measurement of weight. Dalton died July 26, 1844 in Manchester, England. -
Daltons Atomic Theory
Dalton's theory was based on the premise that the atoms of different elements could be distinguished by differences in their weights. He stated his theory in a lecture to the Royal Institution in 1803. The theory proposed a number of basic ideas:
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 -
Dmitri Mendeleev
Dmitri Mendeleev revolutionized our understanding of the properties of atoms and created a table that probably embellishes every chemistry classroom in the world. Known as the periodic table -
Cathode Ray Tube
The development of electronic television systems was based on the development of the cathode ray tube. A cathode ray tube aka picture tube, was found in all electronic television sets up until the invention of the less bulky LCD screens. -
JJ Thomson
His research in cathode rays led to the discovery of the electron, and he pursued further innovations in atomic structure exploration. Thomson won the 1906 Nobel Prize in Physics, among many accolades. He died on August 30, 1940 -
Plum Pudding Atomic Model
The Plum Pudding Model is an atom model proposed by JJ Thomson, the physicist who discovered the electron. It is also known as the Chocolate Chip Cookie or Blueberry Muffin Model. You can easily picture it by imagining the said goodies. For example, you can imagine a plum pudding wherein the pudding itself is positively charged and the plums, dotting the dough, are the negatively charged electron. -
Rutherford Model
In 1894, still at Canterbury, Rutherford conducted independent research on the ability of high-frequency electrical discharge to magnetize iron. His research earned him a Bachelor of Science degree in just one year’s time. By 1919 he had made another monumental discovery: how to artificially induce a nuclear reaction in a stable element. Nuclear reactions were Rutherford’s main focus for the rest of his scientific career. -
Rutherford Model
In 1909 Ernest Rutherford conducted what is now a famous experiment where he bombarded gold foil with alpha particles (Helium nuclei). A source which undergoes alpha decay is placed in a lead box with a small hole in it. Any of the alpha particles which hit the inside of the box are simply stopped by the box. Only those which pass through the opening are allowed to escape, and they follow a straight line to the gold foil. -
Henry Moseley
Henry Moseley is known for his establishment of truly scientific basis of the Periodic Table of the Elements by sorting chemical elements in the order of their atomic numbers. In his short career, he contributed a lot towards the science of physics through his research. -
Niels Bohr
Bohr concentrated the majority of his effort on researching the structure of the atom, and in 1913 he completed his theory of atomic structure. Bohr proposed that the outer orbits could accommodate more electrons than the inner orbits. In total, the atomic structure theory that Bohr proposed included an atom which was 1/10,000 the size of the atoms proposed by other scientists. In 1922, Niels Bohr received the Nobel Prize in Physics for his research in the atomic structure. -
Gold Foil Experiment
Throughout the course of his experiment, Rutherford had his two associates (Hans Geiger and Ernest Marsden) aim a beam of alpha particles at a piece of gold foil that was approximately 8.6 x 10^(-6) centimeters thick. To be more accurate Rutherford actually included a wide variety of different foils (such as: aluminum, iron, and lead), but his use of gold foil is most commonly spoke of. -
Erwin Schrodinger
In 1926 Erwin Schrodinger expained the movement of electrons in an atom. He concluded that it was a wave of motion. He called this idea Wave Mechanics. His discovery was the first to explain the movement of electrons with visuals, and the second to explain the idea. -
Quantum Mechanical Model
Although quantum mechanics was created to describe an abstract atomic world far removed from daily experience, its impact on our daily lives could hardly be greater. The spectacular advances in chemistry, biology, and medicine—and in essentially every other science—could not have occurred without the tools that quantum mechanics made possible. Without quantum mechanics there would be no global economy to speak of, because the electronics revolution that brought us the computer age is a child of -
Ernest Rutherford
n 1911, Rutherford discovered that atoms not independent, they are controlled by something else, a nucleus. He noticed that the majority of an atom's mass is concentrated at a very tiny point in the center where the nucleus was located. The nucleus is a positive force surrounded by electrons which are negative free flying particles. Therefore, he also discovered that there is something smaller than an atom. In 1917, Ernest Rutherford "split the atom" discovering that atoms are made of more than -
James Chadwick
Sir James Chadwick is a very honored scientist. His most famous and exciting discovery was the discovery of the neutron in 1932. He also succeeded in taking apart the atom, which led to the development of the Atomic Bomb, which was used at the end of WWII. The discovery of the neutron not only benefitted him, but it led other scientists to figure out the complete diagram of the atom. -
Electron Cloud Model
The cloud model represents a sort of history of where the electron has probably been and where it is likely to be going. The red dot in the middle represents the nucleus while the red dot around the outside represents an instance of the electron. Imagine, as the electron moves it leaves a trace of where it was. This collection of traces quickly begins to resemble a cloud. The probable locations of the electron predicted by Schrödinger's equation happen to coincide with the locations specifi
