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450 BCE
Four Primal Elements
Empedocles proposes that things are composed of four main elements being earth, air, fire, and water. He was more philosophical stating that human emotions act upon these forces to create various forms. -
Period: 440 BCE to 370 BCE
The Early Atom
Democritus - the first person to use the term atom, meaning invisible. With his scientific background he contributed to early models of the atom.
Developed the theory of the universe; meaning matter consists of atoms. -
Period: 384 BCE to 322 BCE
Aristotle
Greek philosopher Aristotle developed the view that all substances were made of a primary matter, called "hule." This could evolve into different forms from which the elements arose. He determined that there were fundamental properties of matter such as hotness, coldness, moistness and dryness.
384 BCE — 322 BCE -
Period: 1000 to
Alchemy
Alchemists were medieval to modern chemistry. Objectives focused on using compounds and developing their understanding of atoms. Searching for remedies and anything to help the people and the Earth. -
Philosophy
Alchemy and chemistry share an interest in the composition and properties of matter, and prior to the eighteenth century were not separated into distinct disciplines. Alchemists involved with the chemical apparatus developed into chemists searching for the answers of life. -
Robert Boyle
Studied the elemental nature of law. Boyle's law states that, for a given mass, at a constant temperature, the pressure times the volume is a constant. He challenged Aristotle's view of four elements by recognizing that the world could just be system of chemical properties. Boyle was the first to differentiate between compounds and mixtures and proposed that small particles form molecules. -
Carbonated Water
Joseph Priestley developed a method for carbonating beverages in 1767. He recorded instructions for "Impregnating Water With Fixed Air," describing it as an easy process of "first filling any vessel with water, and introducing the fixed air to it, while it stands inverted in another vessel of water." -
Discovery of Oxygen
Joseph Priestley was one of the most 'preeminent' experimental scientists, discovering oxygen. He began experimenting to answer his own questions. Studying the brewery next to his home he discovered oxygen and eight other gases and contributed to the understanding of photosynthesis and respiration. -
Antoine Lavoisier
A French chemist whom developed the metric system. With the assistance of his wife, Marie-Anne Lavoisier and meticulous measurement, the Law of Conversation of Mass was discovered. Additionally the couple produced the rules of naming chemical compounds. -
Atomic Model
John Dalton develops Democritus' theory into the first atomic model. Overall Dalton's life left behind, that atoms were indestructible and unchangeable. -
John Dalton
Proposes atomic theory. He demonstrated that atoms react with each other and that the number of electrons and protons affect the molecule being made. -
Periodic Table
Dmitri Mendeleev's periodic table emerged as the defining document of the elements. Importantly, Mendeleev left spaces open in his table for elements that he thought existed, but were not yet discovered. Later discoveries proved that his predictions were correct. -
Refrigeration
Carl von Linde's invention of the continuous process pf liquefying gases formed a basis for the modern technology of refrigeration and provided both impetus and means for conducting scientific research at low temperatures and very high vacuums. -
J.J Thomson
Thomson discovers that the charge of an atom is invisible. Through experimentation he found that the charge was negative by deflecting off a coil, leading to finding the mass. The charge of the atom is named 'electron.' -
Marie Curie
Marie Curie was not only the first woman to win a Nobel Prize, but is also the sole scientist to receive the Nobel in multiple sciences (Physics in 1903 and later Chemistry in 1911). Henri Becquerel's discovery of radioactivity in 1896 catalyzed Marie and husband Pierre's research, which led to the discovery and isolation of polonium and radium. -
The Gold Foil Experiment
Ernest Rutherford conducts the experiment, firing positively charged particles at a gold piece of foil. Most did not deflect concluding that there must be a positive center to the foil, the nucleus. From this Rutherford establishes the Planetary Model with electrons orbiting the nucleus. -
Niels Bohr
Bohr further developed the planetary model adding energy levels and designated sizes. -
75
The last stable, natural element, rhenium, was discovered in 1925 in Berlin by Ida Tacke and Walter Noddack. It was known at the time that element number 75 should exist, but it had not yet been found. Rhenium is the least abundant stable element on Earth, and thus, no pure samples can be found in nature. -
Period: to
Age of Copper
Metallurgy is chemistry's oldest ancestor, dating back to the Bronze Age, the period when humans learned to smelt copper and tin from natural ores.
