Atomic Theory John Dalton Father of Atomic Theory

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Atomic Theory

Atomic Theory

John Dalton “Father of Atomic Theory”

John Dalton “Father of Atomic Theory”

Dalton’s Atomic Theory All matter is made up of tiny indestructible, indivisible particles, called

Dalton’s Atomic Theory All matter is made up of tiny indestructible, indivisible particles, called atoms All atoms of the same element are identical, and have the same properties Atoms of different elements combine to form compounds Compounds contain atoms in small whole number ratios Atoms can combine in more than one ratio to form different compounds, or simply, chemical reactions involve the rearrangement of atoms. No new atoms are created or destroyed.

Henri Bequerel

Henri Bequerel

Bequerel Model Discovered radioactivity ● Spontaneous emission of radiation from the nucleus Three types:

Bequerel Model Discovered radioactivity ● Spontaneous emission of radiation from the nucleus Three types: ● Alpha (�� ): positive ● Beta (�� ): negative

J. J. Thomson

J. J. Thomson

Thomson’s Plum Pudding Model The atom is breakable Electrons are negative so: Need a

Thomson’s Plum Pudding Model The atom is breakable Electrons are negative so: Need a positive charge to balance the electrons Two negative charges repel each other Electrons are suspended in a positively charged electric field A lot of empty space in the atom to separate the

After Thomson

After Thomson

Milikan Model - American scientist in 1922 - Determined the mass to charge ratio

Milikan Model - American scientist in 1922 - Determined the mass to charge ratio of an electron - Electron charge -1; mass is 9. 11 x 10 -28 g

Ernest Rutherford

Ernest Rutherford

Ernest Rutherford's Model The atom is composed mainly of vacant space All the positive

Ernest Rutherford's Model The atom is composed mainly of vacant space All the positive charge and most of the mass is in a small area called the nucleus The nucleus is dense, which would cause the backward deflection of the �� -particles Negatively charged particles electrons are distributed around a positively charged nucleus An atom has a diameter of ~10 -10 m, whereas the nucleus

Niels Bohr

Niels Bohr

Bohr Model Electrons occupy only certain orbits around the nucleus. Those orbits are stable

Bohr Model Electrons occupy only certain orbits around the nucleus. Those orbits are stable and are called "stationary" orbits. Each orbit has an energy associated with it. The orbit nearest the nucleus has an energy of E 1, the next orbit E 2, etc. Energy is absorbed when an electron jumps from a lower orbit to a higher one and energy is emitted when an electron falls from a higher orbit to a lower orbit. The energy and frequency of light emitted or absorbed can be calculated by using the difference between the two orbital energies.

Erwin Schrödinger

Erwin Schrödinger

Schrodinger Atomic Model Defined an orbital of an atom as: “The region of space

Schrodinger Atomic Model Defined an orbital of an atom as: “The region of space that surrounds a nucleus in which two electrons may randomly move. ” All matter acts as waves, and electrons themselves were wavelike. Electrons were constantly moving and do not have one definite or fixed position in the atom. Electrons are located in probable regions called “Atomic Orbitals” Atomic Orbitals are sorted with energy levels and distributed between electron clouds. Four primary orbitals: s, p, d, and f orbitals

James Chadwick

James Chadwick

James Chadwick Predicted/Discovered the atom would have a neutron. Established that atomic number is

James Chadwick Predicted/Discovered the atom would have a neutron. Established that atomic number is determined by the numbers of protons in an atom. Fundamental discovery in the domain on nuclear science. Neutrons were involved in creating nuclear explosions and nuclear energy, for it is by bombardment with highenergy neutrons that scientists first learned how to split an atom. In this way prepared the way towards the fission of uranium 235 and towards the creation of the atomic bomb.

Atomic Theory Research Project: DUE - Atomic Theory Timeline Handout - Atomic Theory Research

Atomic Theory Research Project: DUE - Atomic Theory Timeline Handout - Atomic Theory Research Group PPT Presentation **Forms posted on Mrs. G’s Website** Must have atomic model image like this one in your PPT presentation for your respective

Atomic Theory Research Project Assignments ● ● ● ● Becquerel Bohr Chadwick Dalton Millikan

Atomic Theory Research Project Assignments ● ● ● ● Becquerel Bohr Chadwick Dalton Millikan Rutherford Schrödinger Thomson