Atomic Timeline

The Alchemists

500 BCE

Believed four elements of the world were water, fire, air, and earth. This was the start of scientific thinking when regarding the atomic theory.

Democritus

450 BCE

Democritus developed that these "atomos" are what make up all matter around us made up of tiny indivisible particles. Democritus significantly took a step in the right direction scientifically by being the first to use the word atom to describe what surrounds everyone.

Plato

427 BCE

Plato came up with this idea that based on the type of element (wind, air, fire, water) there were these different geometric forms for atoms. Plato did not help any advancements in the scientific community by this theory because it was incorrect.

Robert Boyle

1662

Robert Boyle aided in developing the definition of an element. Also, he proved that there were not just the "four elements". Set basis that there are not just four elements and led scientists in the right direction of discussing elements.

Antone Lavoisier

1764

Antone Lavoisier was the scientist who proposed the definition of element and discovered that compounds can be created from elements. Antone helped advance the classification of matter for the scientific community.

John Dalton

1803

Created Dalton's atomic theory which explained how elements are made of tiny particles called atoms. This discovery was an advancement of how scientists perceived what elements were made of.

Billiard Ball Model

1803

Billiard Ball Model was created by John Dalton.

Amedeo Avogadro

1811

Amedeo Avogadro created Amedeo's Law which said elements had the ability to exist as molecules. Amedeo's Law was a large advancement in the scientific community and the classification of matter.

Dmitri Mendeleev

1871

Dmitri Mendeleev founded the first true periodic table of elements. He used the atomic weight to arrange the known elements in order. The atomic weight is used for modern day comparison and classification of elements which is a large help to the scientific community.

JJ Thomson

1896

JJ Thomson discovered atoms had a negatively charged particles called electrons. This discovery positively affected the scientific community by adding a sub-atomic particle to what makes up an atom.

Pierre and Marie Curie

1898

The Curies discovered that atoms had the ability to break down using radioactive particles by finding two elements called polonium and radium. The Curies radioactive discovery was a breakthrough in the scientific community by showing different ways radioactivity can be used to break down atoms.

Plum Pudding Model

1904

Plum Pudding Model was created by JJ Thompson.

Albert Einstein

1905

Albert Einstein proved that atoms existed mathematically in 1905. His use of statistics and probability restructured sciences of the atom.

Robert Millikan

1909

Robert Millikan found out how to measure the charge of an electron. This discovery positively boosted the scientific community in the early 20th century.

Neils Bohr

1911

Neils Bohr invented Bohr's Orbit Model which shows that the nucleus is orbited by electrons in an atom model. This model granted scientists the ability to study a model of how the atom works with a new advancement.

Ernest Rutherford

1911

Ernest Rutherford created Rutherford's atomic model and discovered the positively charged particle in the nucleus of an atom (protons). This led to further improving the early 20th century model of an atom.

Solar System Model

1913

Solar System Model was invented by Neils Bohr.

Henry G. J. Moseley

1914

Henry Moseley discovered that every element has an atomic number directly linked to the number of protons in an atom. Moseley's discovery gave scientists a way to be able to organize different types of atoms.

Erwin Schrödinger

1926

Erwin Schrödinger created the Electron Cloud Model which consisted of a dense nucleus which was orbited by electrons. The model helped scientists better understand the innerworkings and image of the atom.

Electron Cloud Model

1926

Electron Cloud Model was created by Erwin Schrödinger.

Werner Heisenberg

1927

Werner Heisenberg created a mathematical expression to show the different energy levels of electrons within atoms. The mathematical expression he created helped classify the electrons energy levels helping the scientific community better sort and classify different levels of energy given off by electrons.

James Chadwick

1932

James Chadwick discovered that atoms had neutrons in the center of the atom's nucleus. Discovered the final sub-atomic particle that makes up an atom which helped start to finalize the model of an atom and how it works.