The Atomic Model

The Latest Model

1932

End

Discovered neutron.

When beryllium was bombarded with positively charged alpha particles a beam with a high penetrating power was created. James Chadwick discovered that this beam was not deflected by either electric or magnetic fields, meaning it contained neutral particles- neutrons.

James Chadwick

1926

Combined the equations for the behavior of waves with the de Broglie equation to generate a mathematical model for the distribution of electrons in an atom. The advantage of this model is that it consists of mathematical equations known as wave functions that satisfy the requirements placed on the behavior of electrons. The disadvantage is that it is difficult to imagine a physical model of electrons as waves.

Democritus

Contributions

His Discoveries made in 465 B.C.

• All matter consists of invisible particles called atoms.
• Atoms are indestructible.
• Atoms are solid but invisible.
• Atoms differ in size, shape, mass, position, and arrangement.

Robert Millikan

Contribution to the Atom

His atomic theory said that elements consisted of tiny particles called atoms. It states an element is one of a kind (aka pure) because all atoms of an element are identical. All the atoms that make up the element have the same mass. All elements are different from each other due to differing masses.

His atomic theory stated the general information on the atom. Everything is made of atoms.

The Atomic Model

John Dalton

1913

Erwin Schrodinger

Eugen Goldstein

1911

1913

Niels Bohr

Goldstein discovered the Canal Rays in 1886. He discovery that the cathode rays were not the only rays that will move in the opposite direction of the electrons and that the Canal Rays do the same. He discovered that his Canal Rays were positively charged protons and produced a reddish light at the top of the tube and a green color when the electrons hit the sides of the tube. This discovery led to the discovery of the proton.

The model described the atom as a tiny, dense, positively charged core called a nucleus, in which nearly all the mass is concentrated, around which the light, negative constituents, called electrons, circulate at some distance, much like planets revolving around the Sun.

J.J. Thomson

Discovered (1897) the electron, a negatively charged part of every atom. Thomson had discovered that atoms are composite objects, made of pieces with positive and negative charge, and that the negatively charged electrons within the atom were very small compared to the entire atom.

During his work on the atomic structure, he succeeded in working out and presenting a picture of atomic structure that, with later improvements, still serves as clarification on the physical and chemical properties of the elements.

Ernest Rutherford

1858

Hantaro Nagaoka

Max Planck

1903

His quantum theory described the proportionality constant between the energy, E, of a charged atomic oscillator in the wall of a black body, and the frequency, ν, of its associated electromagnetic wave. Its relevance is now integral to the field of quantum mechanics, describing the relationship between energy and frequency, known as the Planck–Einstein relation:

1905

Louis De Broglie

His model resembled a mini-solar system, or the planet Saturn, which is why he called it the "Saturn model". Nagaoka was the first to propose the idea that negatively-charged electrons are located on the outside of the atom

Published equation- E= mc2 -energy and matter are linked together- The energy content of a body is equal to the mass of the body times the speed of light squared quantum theory of light- light exists as tiny packets, called photons.

1925

Albert Einstein

He believed that electrons can act like both particles and waves, just like light. He also said that waves produced by electrons contained in the orbit around the nucleus, set up a standing wave of a certain energy, frequency, and wavelength. He discovered that electrons can act like waves which helped explain some of the things electrons do that we had never been able to explain before.

Wolfgang Pauli

. Werner's discovery helped clarify the modern view of the atom because scientists can compare the actually few numbers of atoms there are, by their movements of electrons, and how many electrons an atom contains. Surrounding the outside of an atomic nucleus is an electron cloud, which is a name given to the electrons that are widely spreading and moving around.

Werner Heisenberg

1925

Explained the behavior of electrons. Electrons orbit nucleus - no two electrons can have same quantum numbers .