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Atomic Theory

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on 2 November 2014

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Transcript of Atomic Theory

Atomic Theory
Christiaan Huygens (1659)
1. Founded the wave they of light.
2. Discovered the true shape of the rings of Saturn.
3. Made original contributions to the science of dynamics; the study of the action of forces on bodies.
Aristotle (348 B.C.)
1. He believed that all substances were made of Fire, Water, Air, and Earth.
2. He did not believe in the atomic theory
3. He believed that the Earth was the center of the Universe
4. Aristotle developed the Scientific Method

Antoine-Laurent de Lavoisier (1780's)
-He used this experiment to help himself come up with the Law of Conservation.
-The Law of Conservation states: That matter cannot be created nor destroyed.
-Rearrangement of matter in reactions.
-Matter rearranged, but never disappeared.
-"Father of Modern Chemistry"
Isaac Newton (1704)
Democritus (400 B.C.)
This is Democritus' Atomic Theory
1.All matter consists of invisible particles called atoms.
Atoms are:
-solid but invisible.
-Atoms differ in size, shape, mass, position, and arrangement.
-Solids are made of small, pointy atoms.
-Liquids are made of large, round atoms.
2.believed that there are an infinite number of atoms.
3.In his words, “The universe is composed of two elements; the atoms and the void in which they exist and move.”

1. Newton formulated a theory of light, the three laws of motion and suggested a mechanical universe with small, solid masses in motion.

The 3 laws of motion:
1.) An object in motion tends to stay in motion unless an external force acts upon it.
2.) When a force acts on an object, it will cause the object to accelerate.
3.) For every action, there is an equal and opposite reaction.

2. Newton suggested that atoms are held together with attractions; forces.
3. "Matter is formed of solid, massy impenetrable particles."
John Dalton (1803)
-All matter was composed of small indivisible particles termed atoms
-Three types of atoms exist:
1. Simple (elements)
2. Compound (simple molecules)
3. Complex (complex molecules).
-Matter is composed of extremely small particles called atoms
-Atoms are indivisible and indestructable
-Atoms of a given element are identical in size, mass, and chemical properties
-Atoms of specific elements are different that those of other elements
-Spherical solid atoms based upon measurable properties of mass.
Johann Jakob Balmer (1885)
- In 1885 he announced a simple formula representing the wavelengths of the spectral lines of hydrogen.
-Discovered a formula basic to the development of atomic theory and the field of atomic spectroscopy.
Dmitri Mendeleev (1869)
- Creation of the periodic table.
-In a dream he states, and later wrote: “In a dream I saw a table where all the elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper.”
-Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law.
Eugen Goldstein (1886)
-Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron.
-Discovery of the proton.
Wilhelm Roentgen (1895)
-Using a CRT he observed that nearby chemicals glowed. Further experiments found very penetrating rays coming from the CRT that were not deflected by a magnetic field. He named them "X-rays".
-He accidentally discovered x-rays.
-Produce and detected electromagnetic radiation; x-rays
Antoine Becquerel (1897)
JJ Thomson (1897-1898)
-Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram. Studied "canal rays" and found they were associated with the proton H + Studied radiations emitted from uranium and thorium and named them alpha and beta.
-Discovered the electron.
-Discovered Isotopes.
-Discovered the Atomic Structure.
Max Planck (1900)
-Used the idea of quanta (discrete units of energy) to explain hot glowing matter.
-The equation is E=Nhf, with E=energy, N=integer, h=constant, f=frequency. In determining this equation, Planck came up with the constant (h), which is now known as "Planck's constant."
Hantaro Nagaoka (1903)
-Postulated a "Saturnian" model of the atom with flat rings of electrons revolving around a positively charged particles.
Albert Einstein (1905)
-Published the famous equation E=mc 2
-Mathematically proved the existence of atoms.
-He was the first person to show a way to prove the existence of atoms; using an ordinary microscope!
Robert Millikan (1909)
-Oil drop experiment determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron.
-Millikan found quite accurate values for the charge and mass of an electron. An atomizer sprayed oil drops into the top chamber and some of them fell through a hole into the chamber between two plates. He used a microscope and a formula to determine the mass of an oil drop from its terminal velocity, which is the speed of a falling object at which gravity and resistance become equal.
Ernest Rutherford (1911)
-Using x-ray tubes, determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number instead of atomic mass.
-An element was named after him.
-Discovered the gold foil experiment.
Niels Bohr (1913)
-Developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of successive orbital shells of electrons.
-He proposed that electrons are arranged in concentric circular orbits around the nucleus
Louis deBroglie (1924)
-Discovered that electrons had a dual nature-similar to both particles and waves. Particle/wave duality. Supported Einstein.
-He created quantum mechanics , which was matter waves
-This shows wave length is inversely proportional To the energy of a particle
-Frequency of matter waves, deduced by him, is directly proportional to the total energy of a particle.
Henry Moseley, (1914)
-Using x-ray tubes, determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number instead of atomic mass.
-Establishment of the Periodic Table
Werner Heisenberg, (1927)
-Described atoms by means of formula connected to the frequencies of spectral lines. Proposed Principle of Indeterminacy- you can not know both the position and velocity of a particle.
Erwin Schrodinger (1930)
-Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom.
-His model predicts the odd of the locations.
James Chadwick, (1932)
-Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.
-Showed the reaction in a proton.
Atomic Theory
Is a theory that describes the structure, behavior, and properties of the atom. It's a chemical theory that states that all matter is composed of units called atoms.
John Alexander Reina Newlands (1864)
-Determined patterns in chemistry.
-He listed the elements in order by increasing atomic weight, which put them into seven families.
-He was the first to assign atomic numbers.
-He failed to leave room in his table for new elements.
-He came up with radioactivity.
-He found this out from unknown x-rays waves, which were produced by uranium.
-He discovered Penetrating radiation.
-He also discovered that uranium was able to expose a photographic plate on black paper, and didn’t depend on the chemical state.
Gilbert Lewis (1902)
Friedrich Hund (1926)
-Discovered the principle of quantum tunneling.
-Helped introduce the method of using molecular orbits to determine the electronic structure of molecules and chemical bonds.
-Did work on the structure of atoms and molecules.
Wolfgang Pauli (1925)
-His famous discovery, the Pauli exclusion principle, which states that no two electrons can exist in the quantum state.
-Introduced his fourth quantum number or a fourth degree of freedom, to explain the characteristics of hydrogen.
-Proposed a quantum number for the “spin” of electrons, with possible values “up” and “down”
-He develops the electron pair theory of acid/base reactions.
-Developed the Lewis dot structures that ultimately led to a complete understanding of the electronic covalent bond.
Jean Foucault (1951)
Murray Gell-Mann (1961)
-He also found that all the elements of an atom are held together by quarks.
-To find this, he blasted high speed electrons into a hydrogen atom.
-Keeping string theory alive.
Glenn T. Seaborg (1851)
-Glenn was known for identifying and discovering elements that were heavier than uranium.
-He also proposed the “actinides” in the element table.
-He discovered these elements just by separating different elements, and combining different elements.
Modern Atomic Theroy
Discoveries of the Atomic Theory
-Discoveries of isotopes
- J.J. Thomas,1902;
Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons.
- J.J. Thomas, 1897;
A stable subatomic particle with a charge of negative electricity .
- James Chadwick, 1932;
A subatomic particle of about the same mass as a proton but without an electric charge.
- Ernest Rutherford, 1911;
He central and most important part of an object
, movement, or group, forming the basis for its activity and growth.
- Ernest Rutherford,1920 (1917);
A stable subatomic particle occurring in all atomic nuclei
, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign.
-Periodic table
-Democritus ,1869;
A table of the chemical elements arranged in order of atomic number
, usually in rows, so that elements with similar atomic structure.
-Quantum numbers
All physics developed this,it changed over the years; A number that occurs in the theoretical expression for the value of some quantized property of a subatomic particle
, atom, or molecule and can only have certain integral or half-integral values.
-Modern atomic theory is, of course, a little more involved than Dalton's theory but the essence of Dalton's theory remains valid. Today we know that atoms can be destroyed via nuclear reactions but not by chemical reactions.
-Many heretofore unexplained chemical phenomena were quickly explained by Dalton with his theory. Dalton's theory quickly became the theoretical foundation in chemistry.
-Aufbau principle
-Niels Bohr, 1920’s;
Is used to determine the electron configuration of an atom, molecule or ion.
-Pauli exclusion principle
- Wolfgang Pauli, 1925;
No two electrons in an atom can have identical quantum numbers.
This is an example of a general principle which applies not only to electrons but also to other particles of half-integer spin.
- Murray-gell Mann, George, 1968;
Any of a number of subatomic particles carrying a fractional electric charge; They have not been directly observed.
-Uncertainty principle
- Werner Heisenberg, 1927;
The principle that the momentum and position of a particle cannot both be precisely determined at the same time.
-Hund's rule
- Friedrich Hund, 1925;
Every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied
, and all electrons in singly occupied orbitals have the same spin
-Scanning tunneling microscope
- Gerd Binning, 1981, and 1986;
A high-resolution microscope using neither light nor an electron beam
, but with an ultrafine tip able to reveal atomic and molecular details of surfaces.
-J.J. Thomson and Carl D Anderson, 1897, and 1936;
A subatomic particle, such as an electron.Doesn't take place inthe strong interaction.
-Gold foil experiments
- Ernest Rutherford, 1911;
Were a landmark series of experiments by which scientists discovered that every atom contains a nucleus where its positive charge and most of its mass is concentrated.
-Cathode ray tubes
- J.J. Thomas, 1897;
a high-vacuum tube in which cathode rays produce a luminous image on a fluorescent screen
, used chiefly in televisions and computer terminals.
-Foucault demonstrated his proof for the first time at the 1851 World's Fair in the Pantheon in Paris.
-He showed that although the pendulum seemed to change its path during the day, -It was actually the floor that was rotating underneath the pendulum.
-Because the floor is attached to the Earth, it must be the Earth that is rotating.
-The Earth is rotating, with a gyroscope.
Gold foil experiment
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