The Atom

Quark

A particle that makes up a proton or neutron, it comes in 6 different flavors. (Sounds like ice cream!)

Compound

A substance formed by 2 elements.

Niels Bohr

Danish physicist that proposed that electrons do not move freely, rather they move in precise steps now known as energy levels.

James Chadwick

Discovered the neutron of the atom in 1932.

Ernest Rutherford

Discovered the nucleus of the arom in 1911.

Eugen Goldstein

Discovered, in 1886, that atoms have positive charges.

Joseph Priestley

English scientist who experimented with mercury calx in 1773, and discovered oxygen.

Antoine Lavoisier

Frenchman who named oxygen.

Amadeo Avogadro

Furthered the understanding of the correct chemical formulas and atomic masses.

Empedocles

Greek philosopher and scientist who argued that all matter was consisted of four elements: Air, Earth, Fire, and Water.

Aristotle

Greek philosopher who accepted the theory of Empedocles, and added his own idea that the 4 elements could be changed to one another, he set back science almost 2000 years.

Democritus

Greek who first came up with the idea of "atomos", which means "indivisible", and he suggested that atomos were specific to the material they made up.

Joseph Gay-Lussac

In 1809, he reported that the hydrogen reacting with oxygen to form water occupied 2× as much volume as the oxygen.

Mass Number

The sum of the number of protons and neutrons an element has in its atomic state.

Subatomic particles

These make up the atom, and they are protons, neutrons, and electrons.

Electron

This subatomic particle circles the nucleus of an atom in a motion called an orbital. It has a negative charge. It also has no mass.

Neutron

This subatomic particle is in the nucleus of the atom, and has a neutral charge,

Proton

This subatomic particle is in the nucleus of the atom, and has a positive charge.

Theory

A unifying scientific explanation supported by testing.

Subatomic

A word meaning "smaller than an atom"

John Dalton

An early 19th century chemis who helped to advance the belief in the existence of atoms.

Joseph Proust

Articulated the Law of Definite Proportions in 1799.

Isotopes

Atoms with the same number of protons but different numbers of neutrons.

Nucleus

The center of an atom, made of protons and neutrons.

Atom

Smallest part of an element that can still retain the properties of that element.

AMU

Stands for Atomic Mass Unit, whuch is an SI unit used to express the mass of atomic particles.

David Bernoulli

Swiss mathematician who developed a theory that air and other gases consist of tiny particles that are too small to be seen.

Evangelista Torricelli

Italian mathematician who showed that air had weight, and invented the barometer.

Atomic Number

Number of protons an element has in its atomic state.

Robert Boyle

Proposed a new definition of an element in around 1660.

Electron cloud

Region around an atom's nucleus in which electrons are likely to be found.

Model

Representation of an object or system.