Introduction to Chemistry: Test 2

Atomic Theory

The concept that all matter is composed of atoms, which are made up of protons, electrons, and neutrons.

Democritus

An ancient Greek philosopher who proposed the idea of atoms, believing that there must be a smallest, fundamental particle of matter.

Dalton

An English chemist, who proposed the atomic model of a tiny, hard, unbreakable sphere.

J.J. Thompson

An English physicist, who discovered the electron and proposed the "choc chip cookie dough" model of the atom with tiny negative electrons embedded in a mass of positive charge.

Rutherford

A New Zealand physicist, who conducted the gold foil experiment and discovered the nucleus of the atom, which contains most of the mass and positive charge.

Bohr

A Danish physicist, who proposed the planetary model of the atom, with electrons orbiting the nucleus in specific energy levels or "orbits".

Quantum Mechanical model

The current model of the atom, which describes electrons as orbiting the atom in random ways and being surrounded by an electron cloud that represents all possible locations of the electron.

Electron

A subatomic particle with a negative charge and a very small mass, located outside the nucleus of an atom.

Proton

A subatomic particle with a positive charge and a mass of approximately 1 atomic mass unit (amu), located inside the nucleus of an atom.

Neutron

A subatomic particle with no charge (neutral) and a mass of approximately 1 atomic mass unit (amu), located inside the nucleus of an atom.