Atomic Theory Review

Democritus

A Greek philosopher who, in 450 BC, stated that all matter was made of various basic elements; that everything is composed of atoms; and that the different properties of atoms could be explained by their being round, pointy, oily, or having hooks.

Bohr Model

An early model of the atom in which electrons were thought to exist in specific (discreet) energy levels and orbit the nucleus in a fixed, circular pathway like planets orbiting the sun.

Plum Pudding Model

An early model of the atom that described it as a positively charged sphere in which negatively charged electrons were randomly scattered.

Discovery of the electron disproved which of Dalton's Postulates>

Atoms are indivisible and indestructable

Neils Bohr

Built on Rutherford's work; developed the Bohr model of the atom in 1913.

Atom

Consists of a dense, central nucleus containing protons and neutrons that is surrounded by a cloud of electrons

JJ Thomson

Discovered the electron in 1897. Developed the Plum Pudding Model. He is credited with the discovery of the electron.

Ernst Rutherford

Discovered the nucleus and proton in 1909. Developed the nuclear model of the atom.

J.J Thomson discovered a subatomic particle that was negatively charged and smaller than the atom. What was it?

Electron

Which subatomic particle are found surrounding the nucleus and have a negative charge

Electron

Gold Foil Experiment

Ernest Rutherford's experiment that led to the discovery of the nucleus as the small, dense, positively charged center of the atom and the development of the nuclear theory of the atom.

Electron

Extremely small, negatively charged particle located in various energy levels outside the nucleus

Cathode Ray Tube Experiment

JJ Thomson's experiment that led to the discovery of the electron and the development of the plum pudding model of the atom

John Dalton

Lived in the early 1800's; Proposed the first comprehensive, accepted atomic theory.

Which subatomic particle is found in the nucleus and have a neutral charge

Neutron

Proton

Positively charged particle located in the nucleus

Which subatomic particle found in the nucleus is positive

Proton

Which subatomic particle is attracted by a negatively charged object

Proton

Which two subatomic particles are contained in the nucleus

Proton and Neutron

Nuclear Atomic Model

Rutherford's theory that stated 1) the atom is mostly empty space; 2) in the center of the atom there is a tiny, positively charged nucleus which contains most of its mass; and 3) electrons are in a fixed orbit in the empty space around the nucleus.

Nucleus

Small, dense, positively charged center of the atom that contains most of its mass

Dalton's Atomic Theory

Stated that 1) each element is made of extremely small particles called atoms that are indivisible; 2) All atoms of a given element are identical, but they differ from those of any other element; 3) Atoms are neither created or destroyed in any chemical rxn; and 4) a given compound always has the same relative #s and kinds of atoms. Proven over time to not be entirely accurate, but it was close!

In the famous experiment conducted by Earnest Rutherford, positively charged alpha particles were scattered by a thin gold foil. What conclusion resulted from this experiment?

The nucleus is very small and the atom is mostly empty space.